1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/os/persistentdata/persistentstorage/sqlite3api/SQLite/select.c Fri Jun 15 03:10:57 2012 +0200
1.3 @@ -0,0 +1,4093 @@
1.4 +/*
1.5 +** 2001 September 15
1.6 +**
1.7 +** The author disclaims copyright to this source code. In place of
1.8 +** a legal notice, here is a blessing:
1.9 +**
1.10 +** May you do good and not evil.
1.11 +** May you find forgiveness for yourself and forgive others.
1.12 +** May you share freely, never taking more than you give.
1.13 +**
1.14 +*************************************************************************
1.15 +** This file contains C code routines that are called by the parser
1.16 +** to handle SELECT statements in SQLite.
1.17 +**
1.18 +** $Id: select.c,v 1.476 2008/09/23 09:36:10 drh Exp $
1.19 +*/
1.20 +#include "sqliteInt.h"
1.21 +
1.22 +
1.23 +/*
1.24 +** Delete all the content of a Select structure but do not deallocate
1.25 +** the select structure itself.
1.26 +*/
1.27 +static void clearSelect(sqlite3 *db, Select *p){
1.28 + sqlite3ExprListDelete(db, p->pEList);
1.29 + sqlite3SrcListDelete(db, p->pSrc);
1.30 + sqlite3ExprDelete(db, p->pWhere);
1.31 + sqlite3ExprListDelete(db, p->pGroupBy);
1.32 + sqlite3ExprDelete(db, p->pHaving);
1.33 + sqlite3ExprListDelete(db, p->pOrderBy);
1.34 + sqlite3SelectDelete(db, p->pPrior);
1.35 + sqlite3ExprDelete(db, p->pLimit);
1.36 + sqlite3ExprDelete(db, p->pOffset);
1.37 +}
1.38 +
1.39 +/*
1.40 +** Initialize a SelectDest structure.
1.41 +*/
1.42 +void sqlite3SelectDestInit(SelectDest *pDest, int eDest, int iParm){
1.43 + pDest->eDest = eDest;
1.44 + pDest->iParm = iParm;
1.45 + pDest->affinity = 0;
1.46 + pDest->iMem = 0;
1.47 + pDest->nMem = 0;
1.48 +}
1.49 +
1.50 +
1.51 +/*
1.52 +** Allocate a new Select structure and return a pointer to that
1.53 +** structure.
1.54 +*/
1.55 +Select *sqlite3SelectNew(
1.56 + Parse *pParse, /* Parsing context */
1.57 + ExprList *pEList, /* which columns to include in the result */
1.58 + SrcList *pSrc, /* the FROM clause -- which tables to scan */
1.59 + Expr *pWhere, /* the WHERE clause */
1.60 + ExprList *pGroupBy, /* the GROUP BY clause */
1.61 + Expr *pHaving, /* the HAVING clause */
1.62 + ExprList *pOrderBy, /* the ORDER BY clause */
1.63 + int isDistinct, /* true if the DISTINCT keyword is present */
1.64 + Expr *pLimit, /* LIMIT value. NULL means not used */
1.65 + Expr *pOffset /* OFFSET value. NULL means no offset */
1.66 +){
1.67 + Select *pNew;
1.68 + Select standin;
1.69 + sqlite3 *db = pParse->db;
1.70 + pNew = sqlite3DbMallocZero(db, sizeof(*pNew) );
1.71 + assert( !pOffset || pLimit ); /* Can't have OFFSET without LIMIT. */
1.72 + if( pNew==0 ){
1.73 + pNew = &standin;
1.74 + memset(pNew, 0, sizeof(*pNew));
1.75 + }
1.76 + if( pEList==0 ){
1.77 + pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db,TK_ALL,0,0,0), 0);
1.78 + }
1.79 + pNew->pEList = pEList;
1.80 + pNew->pSrc = pSrc;
1.81 + pNew->pWhere = pWhere;
1.82 + pNew->pGroupBy = pGroupBy;
1.83 + pNew->pHaving = pHaving;
1.84 + pNew->pOrderBy = pOrderBy;
1.85 + pNew->selFlags = isDistinct ? SF_Distinct : 0;
1.86 + pNew->op = TK_SELECT;
1.87 + assert( pOffset==0 || pLimit!=0 );
1.88 + pNew->pLimit = pLimit;
1.89 + pNew->pOffset = pOffset;
1.90 + pNew->addrOpenEphm[0] = -1;
1.91 + pNew->addrOpenEphm[1] = -1;
1.92 + pNew->addrOpenEphm[2] = -1;
1.93 + if( db->mallocFailed ) {
1.94 + clearSelect(db, pNew);
1.95 + if( pNew!=&standin ) sqlite3DbFree(db, pNew);
1.96 + pNew = 0;
1.97 + }
1.98 + return pNew;
1.99 +}
1.100 +
1.101 +/*
1.102 +** Delete the given Select structure and all of its substructures.
1.103 +*/
1.104 +void sqlite3SelectDelete(sqlite3 *db, Select *p){
1.105 + if( p ){
1.106 + clearSelect(db, p);
1.107 + sqlite3DbFree(db, p);
1.108 + }
1.109 +}
1.110 +
1.111 +/*
1.112 +** Given 1 to 3 identifiers preceeding the JOIN keyword, determine the
1.113 +** type of join. Return an integer constant that expresses that type
1.114 +** in terms of the following bit values:
1.115 +**
1.116 +** JT_INNER
1.117 +** JT_CROSS
1.118 +** JT_OUTER
1.119 +** JT_NATURAL
1.120 +** JT_LEFT
1.121 +** JT_RIGHT
1.122 +**
1.123 +** A full outer join is the combination of JT_LEFT and JT_RIGHT.
1.124 +**
1.125 +** If an illegal or unsupported join type is seen, then still return
1.126 +** a join type, but put an error in the pParse structure.
1.127 +*/
1.128 +int sqlite3JoinType(Parse *pParse, Token *pA, Token *pB, Token *pC){
1.129 + int jointype = 0;
1.130 + Token *apAll[3];
1.131 + Token *p;
1.132 + static const struct {
1.133 + const char zKeyword[8];
1.134 + u8 nChar;
1.135 + u8 code;
1.136 + } keywords[] = {
1.137 + { "natural", 7, JT_NATURAL },
1.138 + { "left", 4, JT_LEFT|JT_OUTER },
1.139 + { "right", 5, JT_RIGHT|JT_OUTER },
1.140 + { "full", 4, JT_LEFT|JT_RIGHT|JT_OUTER },
1.141 + { "outer", 5, JT_OUTER },
1.142 + { "inner", 5, JT_INNER },
1.143 + { "cross", 5, JT_INNER|JT_CROSS },
1.144 + };
1.145 + int i, j;
1.146 + apAll[0] = pA;
1.147 + apAll[1] = pB;
1.148 + apAll[2] = pC;
1.149 + for(i=0; i<3 && apAll[i]; i++){
1.150 + p = apAll[i];
1.151 + for(j=0; j<sizeof(keywords)/sizeof(keywords[0]); j++){
1.152 + if( p->n==keywords[j].nChar
1.153 + && sqlite3StrNICmp((char*)p->z, keywords[j].zKeyword, p->n)==0 ){
1.154 + jointype |= keywords[j].code;
1.155 + break;
1.156 + }
1.157 + }
1.158 + if( j>=sizeof(keywords)/sizeof(keywords[0]) ){
1.159 + jointype |= JT_ERROR;
1.160 + break;
1.161 + }
1.162 + }
1.163 + if(
1.164 + (jointype & (JT_INNER|JT_OUTER))==(JT_INNER|JT_OUTER) ||
1.165 + (jointype & JT_ERROR)!=0
1.166 + ){
1.167 + const char *zSp = " ";
1.168 + assert( pB!=0 );
1.169 + if( pC==0 ){ zSp++; }
1.170 + sqlite3ErrorMsg(pParse, "unknown or unsupported join type: "
1.171 + "%T %T%s%T", pA, pB, zSp, pC);
1.172 + jointype = JT_INNER;
1.173 + }else if( jointype & JT_RIGHT ){
1.174 + sqlite3ErrorMsg(pParse,
1.175 + "RIGHT and FULL OUTER JOINs are not currently supported");
1.176 + jointype = JT_INNER;
1.177 + }
1.178 + return jointype;
1.179 +}
1.180 +
1.181 +/*
1.182 +** Return the index of a column in a table. Return -1 if the column
1.183 +** is not contained in the table.
1.184 +*/
1.185 +static int columnIndex(Table *pTab, const char *zCol){
1.186 + int i;
1.187 + for(i=0; i<pTab->nCol; i++){
1.188 + if( sqlite3StrICmp(pTab->aCol[i].zName, zCol)==0 ) return i;
1.189 + }
1.190 + return -1;
1.191 +}
1.192 +
1.193 +/*
1.194 +** Set the value of a token to a '\000'-terminated string.
1.195 +*/
1.196 +static void setToken(Token *p, const char *z){
1.197 + p->z = (u8*)z;
1.198 + p->n = z ? strlen(z) : 0;
1.199 + p->dyn = 0;
1.200 +}
1.201 +
1.202 +/*
1.203 +** Set the token to the double-quoted and escaped version of the string pointed
1.204 +** to by z. For example;
1.205 +**
1.206 +** {a"bc} -> {"a""bc"}
1.207 +*/
1.208 +static void setQuotedToken(Parse *pParse, Token *p, const char *z){
1.209 +
1.210 + /* Check if the string appears to be quoted using "..." or `...`
1.211 + ** or [...] or '...' or if the string contains any " characters.
1.212 + ** If it does, then record a version of the string with the special
1.213 + ** characters escaped.
1.214 + */
1.215 + const char *z2 = z;
1.216 + if( *z2!='[' && *z2!='`' && *z2!='\'' ){
1.217 + while( *z2 ){
1.218 + if( *z2=='"' ) break;
1.219 + z2++;
1.220 + }
1.221 + }
1.222 +
1.223 + if( *z2 ){
1.224 + /* String contains " characters - copy and quote the string. */
1.225 + p->z = (u8 *)sqlite3MPrintf(pParse->db, "\"%w\"", z);
1.226 + if( p->z ){
1.227 + p->n = strlen((char *)p->z);
1.228 + p->dyn = 1;
1.229 + }
1.230 + }else{
1.231 + /* String contains no " characters - copy the pointer. */
1.232 + p->z = (u8*)z;
1.233 + p->n = (z2 - z);
1.234 + p->dyn = 0;
1.235 + }
1.236 +}
1.237 +
1.238 +/*
1.239 +** Create an expression node for an identifier with the name of zName
1.240 +*/
1.241 +Expr *sqlite3CreateIdExpr(Parse *pParse, const char *zName){
1.242 + Token dummy;
1.243 + setToken(&dummy, zName);
1.244 + return sqlite3PExpr(pParse, TK_ID, 0, 0, &dummy);
1.245 +}
1.246 +
1.247 +/*
1.248 +** Add a term to the WHERE expression in *ppExpr that requires the
1.249 +** zCol column to be equal in the two tables pTab1 and pTab2.
1.250 +*/
1.251 +static void addWhereTerm(
1.252 + Parse *pParse, /* Parsing context */
1.253 + const char *zCol, /* Name of the column */
1.254 + const Table *pTab1, /* First table */
1.255 + const char *zAlias1, /* Alias for first table. May be NULL */
1.256 + const Table *pTab2, /* Second table */
1.257 + const char *zAlias2, /* Alias for second table. May be NULL */
1.258 + int iRightJoinTable, /* VDBE cursor for the right table */
1.259 + Expr **ppExpr, /* Add the equality term to this expression */
1.260 + int isOuterJoin /* True if dealing with an OUTER join */
1.261 +){
1.262 + Expr *pE1a, *pE1b, *pE1c;
1.263 + Expr *pE2a, *pE2b, *pE2c;
1.264 + Expr *pE;
1.265 +
1.266 + pE1a = sqlite3CreateIdExpr(pParse, zCol);
1.267 + pE2a = sqlite3CreateIdExpr(pParse, zCol);
1.268 + if( zAlias1==0 ){
1.269 + zAlias1 = pTab1->zName;
1.270 + }
1.271 + pE1b = sqlite3CreateIdExpr(pParse, zAlias1);
1.272 + if( zAlias2==0 ){
1.273 + zAlias2 = pTab2->zName;
1.274 + }
1.275 + pE2b = sqlite3CreateIdExpr(pParse, zAlias2);
1.276 + pE1c = sqlite3PExpr(pParse, TK_DOT, pE1b, pE1a, 0);
1.277 + pE2c = sqlite3PExpr(pParse, TK_DOT, pE2b, pE2a, 0);
1.278 + pE = sqlite3PExpr(pParse, TK_EQ, pE1c, pE2c, 0);
1.279 + if( pE && isOuterJoin ){
1.280 + ExprSetProperty(pE, EP_FromJoin);
1.281 + pE->iRightJoinTable = iRightJoinTable;
1.282 + }
1.283 + *ppExpr = sqlite3ExprAnd(pParse->db,*ppExpr, pE);
1.284 +}
1.285 +
1.286 +/*
1.287 +** Set the EP_FromJoin property on all terms of the given expression.
1.288 +** And set the Expr.iRightJoinTable to iTable for every term in the
1.289 +** expression.
1.290 +**
1.291 +** The EP_FromJoin property is used on terms of an expression to tell
1.292 +** the LEFT OUTER JOIN processing logic that this term is part of the
1.293 +** join restriction specified in the ON or USING clause and not a part
1.294 +** of the more general WHERE clause. These terms are moved over to the
1.295 +** WHERE clause during join processing but we need to remember that they
1.296 +** originated in the ON or USING clause.
1.297 +**
1.298 +** The Expr.iRightJoinTable tells the WHERE clause processing that the
1.299 +** expression depends on table iRightJoinTable even if that table is not
1.300 +** explicitly mentioned in the expression. That information is needed
1.301 +** for cases like this:
1.302 +**
1.303 +** SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.b AND t1.x=5
1.304 +**
1.305 +** The where clause needs to defer the handling of the t1.x=5
1.306 +** term until after the t2 loop of the join. In that way, a
1.307 +** NULL t2 row will be inserted whenever t1.x!=5. If we do not
1.308 +** defer the handling of t1.x=5, it will be processed immediately
1.309 +** after the t1 loop and rows with t1.x!=5 will never appear in
1.310 +** the output, which is incorrect.
1.311 +*/
1.312 +static void setJoinExpr(Expr *p, int iTable){
1.313 + while( p ){
1.314 + ExprSetProperty(p, EP_FromJoin);
1.315 + p->iRightJoinTable = iTable;
1.316 + setJoinExpr(p->pLeft, iTable);
1.317 + p = p->pRight;
1.318 + }
1.319 +}
1.320 +
1.321 +/*
1.322 +** This routine processes the join information for a SELECT statement.
1.323 +** ON and USING clauses are converted into extra terms of the WHERE clause.
1.324 +** NATURAL joins also create extra WHERE clause terms.
1.325 +**
1.326 +** The terms of a FROM clause are contained in the Select.pSrc structure.
1.327 +** The left most table is the first entry in Select.pSrc. The right-most
1.328 +** table is the last entry. The join operator is held in the entry to
1.329 +** the left. Thus entry 0 contains the join operator for the join between
1.330 +** entries 0 and 1. Any ON or USING clauses associated with the join are
1.331 +** also attached to the left entry.
1.332 +**
1.333 +** This routine returns the number of errors encountered.
1.334 +*/
1.335 +static int sqliteProcessJoin(Parse *pParse, Select *p){
1.336 + SrcList *pSrc; /* All tables in the FROM clause */
1.337 + int i, j; /* Loop counters */
1.338 + struct SrcList_item *pLeft; /* Left table being joined */
1.339 + struct SrcList_item *pRight; /* Right table being joined */
1.340 +
1.341 + pSrc = p->pSrc;
1.342 + pLeft = &pSrc->a[0];
1.343 + pRight = &pLeft[1];
1.344 + for(i=0; i<pSrc->nSrc-1; i++, pRight++, pLeft++){
1.345 + Table *pLeftTab = pLeft->pTab;
1.346 + Table *pRightTab = pRight->pTab;
1.347 + int isOuter;
1.348 +
1.349 + if( pLeftTab==0 || pRightTab==0 ) continue;
1.350 + isOuter = (pRight->jointype & JT_OUTER)!=0;
1.351 +
1.352 + /* When the NATURAL keyword is present, add WHERE clause terms for
1.353 + ** every column that the two tables have in common.
1.354 + */
1.355 + if( pRight->jointype & JT_NATURAL ){
1.356 + if( pRight->pOn || pRight->pUsing ){
1.357 + sqlite3ErrorMsg(pParse, "a NATURAL join may not have "
1.358 + "an ON or USING clause", 0);
1.359 + return 1;
1.360 + }
1.361 + for(j=0; j<pLeftTab->nCol; j++){
1.362 + char *zName = pLeftTab->aCol[j].zName;
1.363 + if( columnIndex(pRightTab, zName)>=0 ){
1.364 + addWhereTerm(pParse, zName, pLeftTab, pLeft->zAlias,
1.365 + pRightTab, pRight->zAlias,
1.366 + pRight->iCursor, &p->pWhere, isOuter);
1.367 +
1.368 + }
1.369 + }
1.370 + }
1.371 +
1.372 + /* Disallow both ON and USING clauses in the same join
1.373 + */
1.374 + if( pRight->pOn && pRight->pUsing ){
1.375 + sqlite3ErrorMsg(pParse, "cannot have both ON and USING "
1.376 + "clauses in the same join");
1.377 + return 1;
1.378 + }
1.379 +
1.380 + /* Add the ON clause to the end of the WHERE clause, connected by
1.381 + ** an AND operator.
1.382 + */
1.383 + if( pRight->pOn ){
1.384 + if( isOuter ) setJoinExpr(pRight->pOn, pRight->iCursor);
1.385 + p->pWhere = sqlite3ExprAnd(pParse->db, p->pWhere, pRight->pOn);
1.386 + pRight->pOn = 0;
1.387 + }
1.388 +
1.389 + /* Create extra terms on the WHERE clause for each column named
1.390 + ** in the USING clause. Example: If the two tables to be joined are
1.391 + ** A and B and the USING clause names X, Y, and Z, then add this
1.392 + ** to the WHERE clause: A.X=B.X AND A.Y=B.Y AND A.Z=B.Z
1.393 + ** Report an error if any column mentioned in the USING clause is
1.394 + ** not contained in both tables to be joined.
1.395 + */
1.396 + if( pRight->pUsing ){
1.397 + IdList *pList = pRight->pUsing;
1.398 + for(j=0; j<pList->nId; j++){
1.399 + char *zName = pList->a[j].zName;
1.400 + if( columnIndex(pLeftTab, zName)<0 || columnIndex(pRightTab, zName)<0 ){
1.401 + sqlite3ErrorMsg(pParse, "cannot join using column %s - column "
1.402 + "not present in both tables", zName);
1.403 + return 1;
1.404 + }
1.405 + addWhereTerm(pParse, zName, pLeftTab, pLeft->zAlias,
1.406 + pRightTab, pRight->zAlias,
1.407 + pRight->iCursor, &p->pWhere, isOuter);
1.408 + }
1.409 + }
1.410 + }
1.411 + return 0;
1.412 +}
1.413 +
1.414 +/*
1.415 +** Insert code into "v" that will push the record on the top of the
1.416 +** stack into the sorter.
1.417 +*/
1.418 +static void pushOntoSorter(
1.419 + Parse *pParse, /* Parser context */
1.420 + ExprList *pOrderBy, /* The ORDER BY clause */
1.421 + Select *pSelect, /* The whole SELECT statement */
1.422 + int regData /* Register holding data to be sorted */
1.423 +){
1.424 + Vdbe *v = pParse->pVdbe;
1.425 + int nExpr = pOrderBy->nExpr;
1.426 + int regBase = sqlite3GetTempRange(pParse, nExpr+2);
1.427 + int regRecord = sqlite3GetTempReg(pParse);
1.428 + sqlite3ExprCodeExprList(pParse, pOrderBy, regBase, 0);
1.429 + sqlite3VdbeAddOp2(v, OP_Sequence, pOrderBy->iECursor, regBase+nExpr);
1.430 + sqlite3ExprCodeMove(pParse, regData, regBase+nExpr+1, 1);
1.431 + sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nExpr + 2, regRecord);
1.432 + sqlite3VdbeAddOp2(v, OP_IdxInsert, pOrderBy->iECursor, regRecord);
1.433 + sqlite3ReleaseTempReg(pParse, regRecord);
1.434 + sqlite3ReleaseTempRange(pParse, regBase, nExpr+2);
1.435 + if( pSelect->iLimit ){
1.436 + int addr1, addr2;
1.437 + int iLimit;
1.438 + if( pSelect->iOffset ){
1.439 + iLimit = pSelect->iOffset+1;
1.440 + }else{
1.441 + iLimit = pSelect->iLimit;
1.442 + }
1.443 + addr1 = sqlite3VdbeAddOp1(v, OP_IfZero, iLimit);
1.444 + sqlite3VdbeAddOp2(v, OP_AddImm, iLimit, -1);
1.445 + addr2 = sqlite3VdbeAddOp0(v, OP_Goto);
1.446 + sqlite3VdbeJumpHere(v, addr1);
1.447 + sqlite3VdbeAddOp1(v, OP_Last, pOrderBy->iECursor);
1.448 + sqlite3VdbeAddOp1(v, OP_Delete, pOrderBy->iECursor);
1.449 + sqlite3VdbeJumpHere(v, addr2);
1.450 + pSelect->iLimit = 0;
1.451 + }
1.452 +}
1.453 +
1.454 +/*
1.455 +** Add code to implement the OFFSET
1.456 +*/
1.457 +static void codeOffset(
1.458 + Vdbe *v, /* Generate code into this VM */
1.459 + Select *p, /* The SELECT statement being coded */
1.460 + int iContinue /* Jump here to skip the current record */
1.461 +){
1.462 + if( p->iOffset && iContinue!=0 ){
1.463 + int addr;
1.464 + sqlite3VdbeAddOp2(v, OP_AddImm, p->iOffset, -1);
1.465 + addr = sqlite3VdbeAddOp1(v, OP_IfNeg, p->iOffset);
1.466 + sqlite3VdbeAddOp2(v, OP_Goto, 0, iContinue);
1.467 + VdbeComment((v, "skip OFFSET records"));
1.468 + sqlite3VdbeJumpHere(v, addr);
1.469 + }
1.470 +}
1.471 +
1.472 +/*
1.473 +** Add code that will check to make sure the N registers starting at iMem
1.474 +** form a distinct entry. iTab is a sorting index that holds previously
1.475 +** seen combinations of the N values. A new entry is made in iTab
1.476 +** if the current N values are new.
1.477 +**
1.478 +** A jump to addrRepeat is made and the N+1 values are popped from the
1.479 +** stack if the top N elements are not distinct.
1.480 +*/
1.481 +static void codeDistinct(
1.482 + Parse *pParse, /* Parsing and code generating context */
1.483 + int iTab, /* A sorting index used to test for distinctness */
1.484 + int addrRepeat, /* Jump to here if not distinct */
1.485 + int N, /* Number of elements */
1.486 + int iMem /* First element */
1.487 +){
1.488 + Vdbe *v;
1.489 + int r1;
1.490 +
1.491 + v = pParse->pVdbe;
1.492 + r1 = sqlite3GetTempReg(pParse);
1.493 + sqlite3VdbeAddOp3(v, OP_MakeRecord, iMem, N, r1);
1.494 + sqlite3VdbeAddOp3(v, OP_Found, iTab, addrRepeat, r1);
1.495 + sqlite3VdbeAddOp2(v, OP_IdxInsert, iTab, r1);
1.496 + sqlite3ReleaseTempReg(pParse, r1);
1.497 +}
1.498 +
1.499 +/*
1.500 +** Generate an error message when a SELECT is used within a subexpression
1.501 +** (example: "a IN (SELECT * FROM table)") but it has more than 1 result
1.502 +** column. We do this in a subroutine because the error occurs in multiple
1.503 +** places.
1.504 +*/
1.505 +static int checkForMultiColumnSelectError(
1.506 + Parse *pParse, /* Parse context. */
1.507 + SelectDest *pDest, /* Destination of SELECT results */
1.508 + int nExpr /* Number of result columns returned by SELECT */
1.509 +){
1.510 + int eDest = pDest->eDest;
1.511 + if( nExpr>1 && (eDest==SRT_Mem || eDest==SRT_Set) ){
1.512 + sqlite3ErrorMsg(pParse, "only a single result allowed for "
1.513 + "a SELECT that is part of an expression");
1.514 + return 1;
1.515 + }else{
1.516 + return 0;
1.517 + }
1.518 +}
1.519 +
1.520 +/*
1.521 +** This routine generates the code for the inside of the inner loop
1.522 +** of a SELECT.
1.523 +**
1.524 +** If srcTab and nColumn are both zero, then the pEList expressions
1.525 +** are evaluated in order to get the data for this row. If nColumn>0
1.526 +** then data is pulled from srcTab and pEList is used only to get the
1.527 +** datatypes for each column.
1.528 +*/
1.529 +static void selectInnerLoop(
1.530 + Parse *pParse, /* The parser context */
1.531 + Select *p, /* The complete select statement being coded */
1.532 + ExprList *pEList, /* List of values being extracted */
1.533 + int srcTab, /* Pull data from this table */
1.534 + int nColumn, /* Number of columns in the source table */
1.535 + ExprList *pOrderBy, /* If not NULL, sort results using this key */
1.536 + int distinct, /* If >=0, make sure results are distinct */
1.537 + SelectDest *pDest, /* How to dispose of the results */
1.538 + int iContinue, /* Jump here to continue with next row */
1.539 + int iBreak /* Jump here to break out of the inner loop */
1.540 +){
1.541 + Vdbe *v = pParse->pVdbe;
1.542 + int i;
1.543 + int hasDistinct; /* True if the DISTINCT keyword is present */
1.544 + int regResult; /* Start of memory holding result set */
1.545 + int eDest = pDest->eDest; /* How to dispose of results */
1.546 + int iParm = pDest->iParm; /* First argument to disposal method */
1.547 + int nResultCol; /* Number of result columns */
1.548 +
1.549 + if( v==0 ) return;
1.550 + assert( pEList!=0 );
1.551 + hasDistinct = distinct>=0;
1.552 + if( pOrderBy==0 && !hasDistinct ){
1.553 + codeOffset(v, p, iContinue);
1.554 + }
1.555 +
1.556 + /* Pull the requested columns.
1.557 + */
1.558 + if( nColumn>0 ){
1.559 + nResultCol = nColumn;
1.560 + }else{
1.561 + nResultCol = pEList->nExpr;
1.562 + }
1.563 + if( pDest->iMem==0 ){
1.564 + pDest->iMem = pParse->nMem+1;
1.565 + pDest->nMem = nResultCol;
1.566 + pParse->nMem += nResultCol;
1.567 + }else if( pDest->nMem!=nResultCol ){
1.568 + /* This happens when two SELECTs of a compound SELECT have differing
1.569 + ** numbers of result columns. The error message will be generated by
1.570 + ** a higher-level routine. */
1.571 + return;
1.572 + }
1.573 + regResult = pDest->iMem;
1.574 + if( nColumn>0 ){
1.575 + for(i=0; i<nColumn; i++){
1.576 + sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, regResult+i);
1.577 + }
1.578 + }else if( eDest!=SRT_Exists ){
1.579 + /* If the destination is an EXISTS(...) expression, the actual
1.580 + ** values returned by the SELECT are not required.
1.581 + */
1.582 + sqlite3ExprCodeExprList(pParse, pEList, regResult, eDest==SRT_Output);
1.583 + }
1.584 + nColumn = nResultCol;
1.585 +
1.586 + /* If the DISTINCT keyword was present on the SELECT statement
1.587 + ** and this row has been seen before, then do not make this row
1.588 + ** part of the result.
1.589 + */
1.590 + if( hasDistinct ){
1.591 + assert( pEList!=0 );
1.592 + assert( pEList->nExpr==nColumn );
1.593 + codeDistinct(pParse, distinct, iContinue, nColumn, regResult);
1.594 + if( pOrderBy==0 ){
1.595 + codeOffset(v, p, iContinue);
1.596 + }
1.597 + }
1.598 +
1.599 + if( checkForMultiColumnSelectError(pParse, pDest, pEList->nExpr) ){
1.600 + return;
1.601 + }
1.602 +
1.603 + switch( eDest ){
1.604 + /* In this mode, write each query result to the key of the temporary
1.605 + ** table iParm.
1.606 + */
1.607 +#ifndef SQLITE_OMIT_COMPOUND_SELECT
1.608 + case SRT_Union: {
1.609 + int r1;
1.610 + r1 = sqlite3GetTempReg(pParse);
1.611 + sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
1.612 + sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1);
1.613 + sqlite3ReleaseTempReg(pParse, r1);
1.614 + break;
1.615 + }
1.616 +
1.617 + /* Construct a record from the query result, but instead of
1.618 + ** saving that record, use it as a key to delete elements from
1.619 + ** the temporary table iParm.
1.620 + */
1.621 + case SRT_Except: {
1.622 + sqlite3VdbeAddOp3(v, OP_IdxDelete, iParm, regResult, nColumn);
1.623 + break;
1.624 + }
1.625 +#endif
1.626 +
1.627 + /* Store the result as data using a unique key.
1.628 + */
1.629 + case SRT_Table:
1.630 + case SRT_EphemTab: {
1.631 + int r1 = sqlite3GetTempReg(pParse);
1.632 + sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
1.633 + if( pOrderBy ){
1.634 + pushOntoSorter(pParse, pOrderBy, p, r1);
1.635 + }else{
1.636 + int r2 = sqlite3GetTempReg(pParse);
1.637 + sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, r2);
1.638 + sqlite3VdbeAddOp3(v, OP_Insert, iParm, r1, r2);
1.639 + sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
1.640 + sqlite3ReleaseTempReg(pParse, r2);
1.641 + }
1.642 + sqlite3ReleaseTempReg(pParse, r1);
1.643 + break;
1.644 + }
1.645 +
1.646 +#ifndef SQLITE_OMIT_SUBQUERY
1.647 + /* If we are creating a set for an "expr IN (SELECT ...)" construct,
1.648 + ** then there should be a single item on the stack. Write this
1.649 + ** item into the set table with bogus data.
1.650 + */
1.651 + case SRT_Set: {
1.652 + assert( nColumn==1 );
1.653 + p->affinity = sqlite3CompareAffinity(pEList->a[0].pExpr, pDest->affinity);
1.654 + if( pOrderBy ){
1.655 + /* At first glance you would think we could optimize out the
1.656 + ** ORDER BY in this case since the order of entries in the set
1.657 + ** does not matter. But there might be a LIMIT clause, in which
1.658 + ** case the order does matter */
1.659 + pushOntoSorter(pParse, pOrderBy, p, regResult);
1.660 + }else{
1.661 + int r1 = sqlite3GetTempReg(pParse);
1.662 + sqlite3VdbeAddOp4(v, OP_MakeRecord, regResult, 1, r1, &p->affinity, 1);
1.663 + sqlite3ExprCacheAffinityChange(pParse, regResult, 1);
1.664 + sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1);
1.665 + sqlite3ReleaseTempReg(pParse, r1);
1.666 + }
1.667 + break;
1.668 + }
1.669 +
1.670 + /* If any row exist in the result set, record that fact and abort.
1.671 + */
1.672 + case SRT_Exists: {
1.673 + sqlite3VdbeAddOp2(v, OP_Integer, 1, iParm);
1.674 + /* The LIMIT clause will terminate the loop for us */
1.675 + break;
1.676 + }
1.677 +
1.678 + /* If this is a scalar select that is part of an expression, then
1.679 + ** store the results in the appropriate memory cell and break out
1.680 + ** of the scan loop.
1.681 + */
1.682 + case SRT_Mem: {
1.683 + assert( nColumn==1 );
1.684 + if( pOrderBy ){
1.685 + pushOntoSorter(pParse, pOrderBy, p, regResult);
1.686 + }else{
1.687 + sqlite3ExprCodeMove(pParse, regResult, iParm, 1);
1.688 + /* The LIMIT clause will jump out of the loop for us */
1.689 + }
1.690 + break;
1.691 + }
1.692 +#endif /* #ifndef SQLITE_OMIT_SUBQUERY */
1.693 +
1.694 + /* Send the data to the callback function or to a subroutine. In the
1.695 + ** case of a subroutine, the subroutine itself is responsible for
1.696 + ** popping the data from the stack.
1.697 + */
1.698 + case SRT_Coroutine:
1.699 + case SRT_Output: {
1.700 + if( pOrderBy ){
1.701 + int r1 = sqlite3GetTempReg(pParse);
1.702 + sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
1.703 + pushOntoSorter(pParse, pOrderBy, p, r1);
1.704 + sqlite3ReleaseTempReg(pParse, r1);
1.705 + }else if( eDest==SRT_Coroutine ){
1.706 + sqlite3VdbeAddOp1(v, OP_Yield, pDest->iParm);
1.707 + }else{
1.708 + sqlite3VdbeAddOp2(v, OP_ResultRow, regResult, nColumn);
1.709 + sqlite3ExprCacheAffinityChange(pParse, regResult, nColumn);
1.710 + }
1.711 + break;
1.712 + }
1.713 +
1.714 +#if !defined(SQLITE_OMIT_TRIGGER)
1.715 + /* Discard the results. This is used for SELECT statements inside
1.716 + ** the body of a TRIGGER. The purpose of such selects is to call
1.717 + ** user-defined functions that have side effects. We do not care
1.718 + ** about the actual results of the select.
1.719 + */
1.720 + default: {
1.721 + assert( eDest==SRT_Discard );
1.722 + break;
1.723 + }
1.724 +#endif
1.725 + }
1.726 +
1.727 + /* Jump to the end of the loop if the LIMIT is reached.
1.728 + */
1.729 + if( p->iLimit ){
1.730 + assert( pOrderBy==0 ); /* If there is an ORDER BY, the call to
1.731 + ** pushOntoSorter() would have cleared p->iLimit */
1.732 + sqlite3VdbeAddOp2(v, OP_AddImm, p->iLimit, -1);
1.733 + sqlite3VdbeAddOp2(v, OP_IfZero, p->iLimit, iBreak);
1.734 + }
1.735 +}
1.736 +
1.737 +/*
1.738 +** Given an expression list, generate a KeyInfo structure that records
1.739 +** the collating sequence for each expression in that expression list.
1.740 +**
1.741 +** If the ExprList is an ORDER BY or GROUP BY clause then the resulting
1.742 +** KeyInfo structure is appropriate for initializing a virtual index to
1.743 +** implement that clause. If the ExprList is the result set of a SELECT
1.744 +** then the KeyInfo structure is appropriate for initializing a virtual
1.745 +** index to implement a DISTINCT test.
1.746 +**
1.747 +** Space to hold the KeyInfo structure is obtain from malloc. The calling
1.748 +** function is responsible for seeing that this structure is eventually
1.749 +** freed. Add the KeyInfo structure to the P4 field of an opcode using
1.750 +** P4_KEYINFO_HANDOFF is the usual way of dealing with this.
1.751 +*/
1.752 +static KeyInfo *keyInfoFromExprList(Parse *pParse, ExprList *pList){
1.753 + sqlite3 *db = pParse->db;
1.754 + int nExpr;
1.755 + KeyInfo *pInfo;
1.756 + struct ExprList_item *pItem;
1.757 + int i;
1.758 +
1.759 + nExpr = pList->nExpr;
1.760 + pInfo = sqlite3DbMallocZero(db, sizeof(*pInfo) + nExpr*(sizeof(CollSeq*)+1) );
1.761 + if( pInfo ){
1.762 + pInfo->aSortOrder = (u8*)&pInfo->aColl[nExpr];
1.763 + pInfo->nField = nExpr;
1.764 + pInfo->enc = ENC(db);
1.765 + for(i=0, pItem=pList->a; i<nExpr; i++, pItem++){
1.766 + CollSeq *pColl;
1.767 + pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr);
1.768 + if( !pColl ){
1.769 + pColl = db->pDfltColl;
1.770 + }
1.771 + pInfo->aColl[i] = pColl;
1.772 + pInfo->aSortOrder[i] = pItem->sortOrder;
1.773 + }
1.774 + }
1.775 + return pInfo;
1.776 +}
1.777 +
1.778 +
1.779 +/*
1.780 +** If the inner loop was generated using a non-null pOrderBy argument,
1.781 +** then the results were placed in a sorter. After the loop is terminated
1.782 +** we need to run the sorter and output the results. The following
1.783 +** routine generates the code needed to do that.
1.784 +*/
1.785 +static void generateSortTail(
1.786 + Parse *pParse, /* Parsing context */
1.787 + Select *p, /* The SELECT statement */
1.788 + Vdbe *v, /* Generate code into this VDBE */
1.789 + int nColumn, /* Number of columns of data */
1.790 + SelectDest *pDest /* Write the sorted results here */
1.791 +){
1.792 + int brk = sqlite3VdbeMakeLabel(v);
1.793 + int cont = sqlite3VdbeMakeLabel(v);
1.794 + int addr;
1.795 + int iTab;
1.796 + int pseudoTab = 0;
1.797 + ExprList *pOrderBy = p->pOrderBy;
1.798 +
1.799 + int eDest = pDest->eDest;
1.800 + int iParm = pDest->iParm;
1.801 +
1.802 + int regRow;
1.803 + int regRowid;
1.804 +
1.805 + iTab = pOrderBy->iECursor;
1.806 + if( eDest==SRT_Output || eDest==SRT_Coroutine ){
1.807 + pseudoTab = pParse->nTab++;
1.808 + sqlite3VdbeAddOp2(v, OP_SetNumColumns, 0, nColumn);
1.809 + sqlite3VdbeAddOp2(v, OP_OpenPseudo, pseudoTab, eDest==SRT_Output);
1.810 + }
1.811 + addr = 1 + sqlite3VdbeAddOp2(v, OP_Sort, iTab, brk);
1.812 + codeOffset(v, p, cont);
1.813 + regRow = sqlite3GetTempReg(pParse);
1.814 + regRowid = sqlite3GetTempReg(pParse);
1.815 + sqlite3VdbeAddOp3(v, OP_Column, iTab, pOrderBy->nExpr + 1, regRow);
1.816 + switch( eDest ){
1.817 + case SRT_Table:
1.818 + case SRT_EphemTab: {
1.819 + sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, regRowid);
1.820 + sqlite3VdbeAddOp3(v, OP_Insert, iParm, regRow, regRowid);
1.821 + sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
1.822 + break;
1.823 + }
1.824 +#ifndef SQLITE_OMIT_SUBQUERY
1.825 + case SRT_Set: {
1.826 + assert( nColumn==1 );
1.827 + sqlite3VdbeAddOp4(v, OP_MakeRecord, regRow, 1, regRowid, &p->affinity, 1);
1.828 + sqlite3ExprCacheAffinityChange(pParse, regRow, 1);
1.829 + sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, regRowid);
1.830 + break;
1.831 + }
1.832 + case SRT_Mem: {
1.833 + assert( nColumn==1 );
1.834 + sqlite3ExprCodeMove(pParse, regRow, iParm, 1);
1.835 + /* The LIMIT clause will terminate the loop for us */
1.836 + break;
1.837 + }
1.838 +#endif
1.839 + case SRT_Output:
1.840 + case SRT_Coroutine: {
1.841 + int i;
1.842 + sqlite3VdbeAddOp2(v, OP_Integer, 1, regRowid);
1.843 + sqlite3VdbeAddOp3(v, OP_Insert, pseudoTab, regRow, regRowid);
1.844 + for(i=0; i<nColumn; i++){
1.845 + assert( regRow!=pDest->iMem+i );
1.846 + sqlite3VdbeAddOp3(v, OP_Column, pseudoTab, i, pDest->iMem+i);
1.847 + }
1.848 + if( eDest==SRT_Output ){
1.849 + sqlite3VdbeAddOp2(v, OP_ResultRow, pDest->iMem, nColumn);
1.850 + sqlite3ExprCacheAffinityChange(pParse, pDest->iMem, nColumn);
1.851 + }else{
1.852 + sqlite3VdbeAddOp1(v, OP_Yield, pDest->iParm);
1.853 + }
1.854 + break;
1.855 + }
1.856 + default: {
1.857 + /* Do nothing */
1.858 + break;
1.859 + }
1.860 + }
1.861 + sqlite3ReleaseTempReg(pParse, regRow);
1.862 + sqlite3ReleaseTempReg(pParse, regRowid);
1.863 +
1.864 + /* LIMIT has been implemented by the pushOntoSorter() routine.
1.865 + */
1.866 + assert( p->iLimit==0 );
1.867 +
1.868 + /* The bottom of the loop
1.869 + */
1.870 + sqlite3VdbeResolveLabel(v, cont);
1.871 + sqlite3VdbeAddOp2(v, OP_Next, iTab, addr);
1.872 + sqlite3VdbeResolveLabel(v, brk);
1.873 + if( eDest==SRT_Output || eDest==SRT_Coroutine ){
1.874 + sqlite3VdbeAddOp2(v, OP_Close, pseudoTab, 0);
1.875 + }
1.876 +
1.877 +}
1.878 +
1.879 +/*
1.880 +** Return a pointer to a string containing the 'declaration type' of the
1.881 +** expression pExpr. The string may be treated as static by the caller.
1.882 +**
1.883 +** The declaration type is the exact datatype definition extracted from the
1.884 +** original CREATE TABLE statement if the expression is a column. The
1.885 +** declaration type for a ROWID field is INTEGER. Exactly when an expression
1.886 +** is considered a column can be complex in the presence of subqueries. The
1.887 +** result-set expression in all of the following SELECT statements is
1.888 +** considered a column by this function.
1.889 +**
1.890 +** SELECT col FROM tbl;
1.891 +** SELECT (SELECT col FROM tbl;
1.892 +** SELECT (SELECT col FROM tbl);
1.893 +** SELECT abc FROM (SELECT col AS abc FROM tbl);
1.894 +**
1.895 +** The declaration type for any expression other than a column is NULL.
1.896 +*/
1.897 +static const char *columnType(
1.898 + NameContext *pNC,
1.899 + Expr *pExpr,
1.900 + const char **pzOriginDb,
1.901 + const char **pzOriginTab,
1.902 + const char **pzOriginCol
1.903 +){
1.904 + char const *zType = 0;
1.905 + char const *zOriginDb = 0;
1.906 + char const *zOriginTab = 0;
1.907 + char const *zOriginCol = 0;
1.908 + int j;
1.909 + if( pExpr==0 || pNC->pSrcList==0 ) return 0;
1.910 +
1.911 + switch( pExpr->op ){
1.912 + case TK_AGG_COLUMN:
1.913 + case TK_COLUMN: {
1.914 + /* The expression is a column. Locate the table the column is being
1.915 + ** extracted from in NameContext.pSrcList. This table may be real
1.916 + ** database table or a subquery.
1.917 + */
1.918 + Table *pTab = 0; /* Table structure column is extracted from */
1.919 + Select *pS = 0; /* Select the column is extracted from */
1.920 + int iCol = pExpr->iColumn; /* Index of column in pTab */
1.921 + while( pNC && !pTab ){
1.922 + SrcList *pTabList = pNC->pSrcList;
1.923 + for(j=0;j<pTabList->nSrc && pTabList->a[j].iCursor!=pExpr->iTable;j++);
1.924 + if( j<pTabList->nSrc ){
1.925 + pTab = pTabList->a[j].pTab;
1.926 + pS = pTabList->a[j].pSelect;
1.927 + }else{
1.928 + pNC = pNC->pNext;
1.929 + }
1.930 + }
1.931 +
1.932 + if( pTab==0 ){
1.933 + /* FIX ME:
1.934 + ** This can occurs if you have something like "SELECT new.x;" inside
1.935 + ** a trigger. In other words, if you reference the special "new"
1.936 + ** table in the result set of a select. We do not have a good way
1.937 + ** to find the actual table type, so call it "TEXT". This is really
1.938 + ** something of a bug, but I do not know how to fix it.
1.939 + **
1.940 + ** This code does not produce the correct answer - it just prevents
1.941 + ** a segfault. See ticket #1229.
1.942 + */
1.943 + zType = "TEXT";
1.944 + break;
1.945 + }
1.946 +
1.947 + assert( pTab );
1.948 + if( pS ){
1.949 + /* The "table" is actually a sub-select or a view in the FROM clause
1.950 + ** of the SELECT statement. Return the declaration type and origin
1.951 + ** data for the result-set column of the sub-select.
1.952 + */
1.953 + if( iCol>=0 && iCol<pS->pEList->nExpr ){
1.954 + /* If iCol is less than zero, then the expression requests the
1.955 + ** rowid of the sub-select or view. This expression is legal (see
1.956 + ** test case misc2.2.2) - it always evaluates to NULL.
1.957 + */
1.958 + NameContext sNC;
1.959 + Expr *p = pS->pEList->a[iCol].pExpr;
1.960 + sNC.pSrcList = pS->pSrc;
1.961 + sNC.pNext = 0;
1.962 + sNC.pParse = pNC->pParse;
1.963 + zType = columnType(&sNC, p, &zOriginDb, &zOriginTab, &zOriginCol);
1.964 + }
1.965 + }else if( pTab->pSchema ){
1.966 + /* A real table */
1.967 + assert( !pS );
1.968 + if( iCol<0 ) iCol = pTab->iPKey;
1.969 + assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) );
1.970 + if( iCol<0 ){
1.971 + zType = "INTEGER";
1.972 + zOriginCol = "rowid";
1.973 + }else{
1.974 + zType = pTab->aCol[iCol].zType;
1.975 + zOriginCol = pTab->aCol[iCol].zName;
1.976 + }
1.977 + zOriginTab = pTab->zName;
1.978 + if( pNC->pParse ){
1.979 + int iDb = sqlite3SchemaToIndex(pNC->pParse->db, pTab->pSchema);
1.980 + zOriginDb = pNC->pParse->db->aDb[iDb].zName;
1.981 + }
1.982 + }
1.983 + break;
1.984 + }
1.985 +#ifndef SQLITE_OMIT_SUBQUERY
1.986 + case TK_SELECT: {
1.987 + /* The expression is a sub-select. Return the declaration type and
1.988 + ** origin info for the single column in the result set of the SELECT
1.989 + ** statement.
1.990 + */
1.991 + NameContext sNC;
1.992 + Select *pS = pExpr->pSelect;
1.993 + Expr *p = pS->pEList->a[0].pExpr;
1.994 + sNC.pSrcList = pS->pSrc;
1.995 + sNC.pNext = pNC;
1.996 + sNC.pParse = pNC->pParse;
1.997 + zType = columnType(&sNC, p, &zOriginDb, &zOriginTab, &zOriginCol);
1.998 + break;
1.999 + }
1.1000 +#endif
1.1001 + }
1.1002 +
1.1003 + if( pzOriginDb ){
1.1004 + assert( pzOriginTab && pzOriginCol );
1.1005 + *pzOriginDb = zOriginDb;
1.1006 + *pzOriginTab = zOriginTab;
1.1007 + *pzOriginCol = zOriginCol;
1.1008 + }
1.1009 + return zType;
1.1010 +}
1.1011 +
1.1012 +/*
1.1013 +** Generate code that will tell the VDBE the declaration types of columns
1.1014 +** in the result set.
1.1015 +*/
1.1016 +static void generateColumnTypes(
1.1017 + Parse *pParse, /* Parser context */
1.1018 + SrcList *pTabList, /* List of tables */
1.1019 + ExprList *pEList /* Expressions defining the result set */
1.1020 +){
1.1021 +#ifndef SQLITE_OMIT_DECLTYPE
1.1022 + Vdbe *v = pParse->pVdbe;
1.1023 + int i;
1.1024 + NameContext sNC;
1.1025 + sNC.pSrcList = pTabList;
1.1026 + sNC.pParse = pParse;
1.1027 + for(i=0; i<pEList->nExpr; i++){
1.1028 + Expr *p = pEList->a[i].pExpr;
1.1029 + const char *zType;
1.1030 +#ifdef SQLITE_ENABLE_COLUMN_METADATA
1.1031 + const char *zOrigDb = 0;
1.1032 + const char *zOrigTab = 0;
1.1033 + const char *zOrigCol = 0;
1.1034 + zType = columnType(&sNC, p, &zOrigDb, &zOrigTab, &zOrigCol);
1.1035 +
1.1036 + /* The vdbe must make its own copy of the column-type and other
1.1037 + ** column specific strings, in case the schema is reset before this
1.1038 + ** virtual machine is deleted.
1.1039 + */
1.1040 + sqlite3VdbeSetColName(v, i, COLNAME_DATABASE, zOrigDb, P4_TRANSIENT);
1.1041 + sqlite3VdbeSetColName(v, i, COLNAME_TABLE, zOrigTab, P4_TRANSIENT);
1.1042 + sqlite3VdbeSetColName(v, i, COLNAME_COLUMN, zOrigCol, P4_TRANSIENT);
1.1043 +#else
1.1044 + zType = columnType(&sNC, p, 0, 0, 0);
1.1045 +#endif
1.1046 + sqlite3VdbeSetColName(v, i, COLNAME_DECLTYPE, zType, P4_TRANSIENT);
1.1047 + }
1.1048 +#endif /* SQLITE_OMIT_DECLTYPE */
1.1049 +}
1.1050 +
1.1051 +/*
1.1052 +** Generate code that will tell the VDBE the names of columns
1.1053 +** in the result set. This information is used to provide the
1.1054 +** azCol[] values in the callback.
1.1055 +*/
1.1056 +static void generateColumnNames(
1.1057 + Parse *pParse, /* Parser context */
1.1058 + SrcList *pTabList, /* List of tables */
1.1059 + ExprList *pEList /* Expressions defining the result set */
1.1060 +){
1.1061 + Vdbe *v = pParse->pVdbe;
1.1062 + int i, j;
1.1063 + sqlite3 *db = pParse->db;
1.1064 + int fullNames, shortNames;
1.1065 +
1.1066 +#ifndef SQLITE_OMIT_EXPLAIN
1.1067 + /* If this is an EXPLAIN, skip this step */
1.1068 + if( pParse->explain ){
1.1069 + return;
1.1070 + }
1.1071 +#endif
1.1072 +
1.1073 + assert( v!=0 );
1.1074 + if( pParse->colNamesSet || v==0 || db->mallocFailed ) return;
1.1075 + pParse->colNamesSet = 1;
1.1076 + fullNames = (db->flags & SQLITE_FullColNames)!=0;
1.1077 + shortNames = (db->flags & SQLITE_ShortColNames)!=0;
1.1078 + sqlite3VdbeSetNumCols(v, pEList->nExpr);
1.1079 + for(i=0; i<pEList->nExpr; i++){
1.1080 + Expr *p;
1.1081 + p = pEList->a[i].pExpr;
1.1082 + if( p==0 ) continue;
1.1083 + if( pEList->a[i].zName ){
1.1084 + char *zName = pEList->a[i].zName;
1.1085 + sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, strlen(zName));
1.1086 + }else if( (p->op==TK_COLUMN || p->op==TK_AGG_COLUMN) && pTabList ){
1.1087 + Table *pTab;
1.1088 + char *zCol;
1.1089 + int iCol = p->iColumn;
1.1090 + for(j=0; j<pTabList->nSrc && pTabList->a[j].iCursor!=p->iTable; j++){}
1.1091 + assert( j<pTabList->nSrc );
1.1092 + pTab = pTabList->a[j].pTab;
1.1093 + if( iCol<0 ) iCol = pTab->iPKey;
1.1094 + assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) );
1.1095 + if( iCol<0 ){
1.1096 + zCol = "rowid";
1.1097 + }else{
1.1098 + zCol = pTab->aCol[iCol].zName;
1.1099 + }
1.1100 + if( !shortNames && !fullNames ){
1.1101 + sqlite3VdbeSetColName(v, i, COLNAME_NAME, (char*)p->span.z, p->span.n);
1.1102 + }else if( fullNames || (!shortNames && pTabList->nSrc>1) ){
1.1103 + char *zName = 0;
1.1104 + char *zTab;
1.1105 +
1.1106 + zTab = pTabList->a[j].zAlias;
1.1107 + if( fullNames || zTab==0 ) zTab = pTab->zName;
1.1108 + zName = sqlite3MPrintf(db, "%s.%s", zTab, zCol);
1.1109 + sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, P4_DYNAMIC);
1.1110 + }else{
1.1111 + sqlite3VdbeSetColName(v, i, COLNAME_NAME, zCol, strlen(zCol));
1.1112 + }
1.1113 + }else{
1.1114 + sqlite3VdbeSetColName(v, i, COLNAME_NAME, (char*)p->span.z, p->span.n);
1.1115 + }
1.1116 + }
1.1117 + generateColumnTypes(pParse, pTabList, pEList);
1.1118 +}
1.1119 +
1.1120 +#ifndef SQLITE_OMIT_COMPOUND_SELECT
1.1121 +/*
1.1122 +** Name of the connection operator, used for error messages.
1.1123 +*/
1.1124 +static const char *selectOpName(int id){
1.1125 + char *z;
1.1126 + switch( id ){
1.1127 + case TK_ALL: z = "UNION ALL"; break;
1.1128 + case TK_INTERSECT: z = "INTERSECT"; break;
1.1129 + case TK_EXCEPT: z = "EXCEPT"; break;
1.1130 + default: z = "UNION"; break;
1.1131 + }
1.1132 + return z;
1.1133 +}
1.1134 +#endif /* SQLITE_OMIT_COMPOUND_SELECT */
1.1135 +
1.1136 +/*
1.1137 +** Given a an expression list (which is really the list of expressions
1.1138 +** that form the result set of a SELECT statement) compute appropriate
1.1139 +** column names for a table that would hold the expression list.
1.1140 +**
1.1141 +** All column names will be unique.
1.1142 +**
1.1143 +** Only the column names are computed. Column.zType, Column.zColl,
1.1144 +** and other fields of Column are zeroed.
1.1145 +**
1.1146 +** Return SQLITE_OK on success. If a memory allocation error occurs,
1.1147 +** store NULL in *paCol and 0 in *pnCol and return SQLITE_NOMEM.
1.1148 +*/
1.1149 +static int selectColumnsFromExprList(
1.1150 + Parse *pParse, /* Parsing context */
1.1151 + ExprList *pEList, /* Expr list from which to derive column names */
1.1152 + int *pnCol, /* Write the number of columns here */
1.1153 + Column **paCol /* Write the new column list here */
1.1154 +){
1.1155 + sqlite3 *db = pParse->db;
1.1156 + int i, j, cnt;
1.1157 + Column *aCol, *pCol;
1.1158 + int nCol;
1.1159 + Expr *p;
1.1160 + char *zName;
1.1161 + int nName;
1.1162 +
1.1163 + *pnCol = nCol = pEList->nExpr;
1.1164 + aCol = *paCol = sqlite3DbMallocZero(db, sizeof(aCol[0])*nCol);
1.1165 + if( aCol==0 ) return SQLITE_NOMEM;
1.1166 + for(i=0, pCol=aCol; i<nCol; i++, pCol++){
1.1167 + /* Get an appropriate name for the column
1.1168 + */
1.1169 + p = pEList->a[i].pExpr;
1.1170 + assert( p->pRight==0 || p->pRight->token.z==0 || p->pRight->token.z[0]!=0 );
1.1171 + if( (zName = pEList->a[i].zName)!=0 ){
1.1172 + /* If the column contains an "AS <name>" phrase, use <name> as the name */
1.1173 + zName = sqlite3DbStrDup(db, zName);
1.1174 + }else{
1.1175 + Expr *pCol = p;
1.1176 + Table *pTab;
1.1177 + while( pCol->op==TK_DOT ) pCol = pCol->pRight;
1.1178 + if( pCol->op==TK_COLUMN && (pTab = pCol->pTab)!=0 ){
1.1179 + /* For columns use the column name name */
1.1180 + int iCol = pCol->iColumn;
1.1181 + if( iCol<0 ) iCol = pTab->iPKey;
1.1182 + zName = sqlite3MPrintf(db, "%s",
1.1183 + iCol>=0 ? pTab->aCol[iCol].zName : "rowid");
1.1184 + }else{
1.1185 + /* Use the original text of the column expression as its name */
1.1186 + zName = sqlite3MPrintf(db, "%T", &pCol->span);
1.1187 + }
1.1188 + }
1.1189 + if( db->mallocFailed ){
1.1190 + sqlite3DbFree(db, zName);
1.1191 + break;
1.1192 + }
1.1193 + sqlite3Dequote(zName);
1.1194 +
1.1195 + /* Make sure the column name is unique. If the name is not unique,
1.1196 + ** append a integer to the name so that it becomes unique.
1.1197 + */
1.1198 + nName = strlen(zName);
1.1199 + for(j=cnt=0; j<i; j++){
1.1200 + if( sqlite3StrICmp(aCol[j].zName, zName)==0 ){
1.1201 + char *zNewName;
1.1202 + zName[nName] = 0;
1.1203 + zNewName = sqlite3MPrintf(db, "%s:%d", zName, ++cnt);
1.1204 + sqlite3DbFree(db, zName);
1.1205 + zName = zNewName;
1.1206 + j = -1;
1.1207 + if( zName==0 ) break;
1.1208 + }
1.1209 + }
1.1210 + pCol->zName = zName;
1.1211 + }
1.1212 + if( db->mallocFailed ){
1.1213 + int j;
1.1214 + for(j=0; j<i; j++){
1.1215 + sqlite3DbFree(db, aCol[j].zName);
1.1216 + }
1.1217 + sqlite3DbFree(db, aCol);
1.1218 + *paCol = 0;
1.1219 + *pnCol = 0;
1.1220 + return SQLITE_NOMEM;
1.1221 + }
1.1222 + return SQLITE_OK;
1.1223 +}
1.1224 +
1.1225 +/*
1.1226 +** Add type and collation information to a column list based on
1.1227 +** a SELECT statement.
1.1228 +**
1.1229 +** The column list presumably came from selectColumnNamesFromExprList().
1.1230 +** The column list has only names, not types or collations. This
1.1231 +** routine goes through and adds the types and collations.
1.1232 +**
1.1233 +** This routine requires that all indentifiers in the SELECT
1.1234 +** statement be resolved.
1.1235 +*/
1.1236 +static void selectAddColumnTypeAndCollation(
1.1237 + Parse *pParse, /* Parsing contexts */
1.1238 + int nCol, /* Number of columns */
1.1239 + Column *aCol, /* List of columns */
1.1240 + Select *pSelect /* SELECT used to determine types and collations */
1.1241 +){
1.1242 + sqlite3 *db = pParse->db;
1.1243 + NameContext sNC;
1.1244 + Column *pCol;
1.1245 + CollSeq *pColl;
1.1246 + int i;
1.1247 + Expr *p;
1.1248 + struct ExprList_item *a;
1.1249 +
1.1250 + assert( pSelect!=0 );
1.1251 + assert( (pSelect->selFlags & SF_Resolved)!=0 );
1.1252 + assert( nCol==pSelect->pEList->nExpr || db->mallocFailed );
1.1253 + if( db->mallocFailed ) return;
1.1254 + memset(&sNC, 0, sizeof(sNC));
1.1255 + sNC.pSrcList = pSelect->pSrc;
1.1256 + a = pSelect->pEList->a;
1.1257 + for(i=0, pCol=aCol; i<nCol; i++, pCol++){
1.1258 + p = a[i].pExpr;
1.1259 + pCol->zType = sqlite3DbStrDup(db, columnType(&sNC, p, 0, 0, 0));
1.1260 + pCol->affinity = sqlite3ExprAffinity(p);
1.1261 + pColl = sqlite3ExprCollSeq(pParse, p);
1.1262 + if( pColl ){
1.1263 + pCol->zColl = sqlite3DbStrDup(db, pColl->zName);
1.1264 + }
1.1265 + }
1.1266 +}
1.1267 +
1.1268 +/*
1.1269 +** Given a SELECT statement, generate a Table structure that describes
1.1270 +** the result set of that SELECT.
1.1271 +*/
1.1272 +Table *sqlite3ResultSetOfSelect(Parse *pParse, Select *pSelect){
1.1273 + Table *pTab;
1.1274 + sqlite3 *db = pParse->db;
1.1275 + int savedFlags;
1.1276 +
1.1277 + savedFlags = db->flags;
1.1278 + db->flags &= ~SQLITE_FullColNames;
1.1279 + db->flags |= SQLITE_ShortColNames;
1.1280 + sqlite3SelectPrep(pParse, pSelect, 0);
1.1281 + if( pParse->nErr ) return 0;
1.1282 + while( pSelect->pPrior ) pSelect = pSelect->pPrior;
1.1283 + db->flags = savedFlags;
1.1284 + pTab = sqlite3DbMallocZero(db, sizeof(Table) );
1.1285 + if( pTab==0 ){
1.1286 + return 0;
1.1287 + }
1.1288 + pTab->db = db;
1.1289 + pTab->nRef = 1;
1.1290 + pTab->zName = 0;
1.1291 + selectColumnsFromExprList(pParse, pSelect->pEList, &pTab->nCol, &pTab->aCol);
1.1292 + selectAddColumnTypeAndCollation(pParse, pTab->nCol, pTab->aCol, pSelect);
1.1293 + pTab->iPKey = -1;
1.1294 + if( db->mallocFailed ){
1.1295 + sqlite3DeleteTable(pTab);
1.1296 + return 0;
1.1297 + }
1.1298 + return pTab;
1.1299 +}
1.1300 +
1.1301 +/*
1.1302 +** Get a VDBE for the given parser context. Create a new one if necessary.
1.1303 +** If an error occurs, return NULL and leave a message in pParse.
1.1304 +*/
1.1305 +Vdbe *sqlite3GetVdbe(Parse *pParse){
1.1306 + Vdbe *v = pParse->pVdbe;
1.1307 + if( v==0 ){
1.1308 + v = pParse->pVdbe = sqlite3VdbeCreate(pParse->db);
1.1309 +#ifndef SQLITE_OMIT_TRACE
1.1310 + if( v ){
1.1311 + sqlite3VdbeAddOp0(v, OP_Trace);
1.1312 + }
1.1313 +#endif
1.1314 + }
1.1315 + return v;
1.1316 +}
1.1317 +
1.1318 +
1.1319 +/*
1.1320 +** Compute the iLimit and iOffset fields of the SELECT based on the
1.1321 +** pLimit and pOffset expressions. pLimit and pOffset hold the expressions
1.1322 +** that appear in the original SQL statement after the LIMIT and OFFSET
1.1323 +** keywords. Or NULL if those keywords are omitted. iLimit and iOffset
1.1324 +** are the integer memory register numbers for counters used to compute
1.1325 +** the limit and offset. If there is no limit and/or offset, then
1.1326 +** iLimit and iOffset are negative.
1.1327 +**
1.1328 +** This routine changes the values of iLimit and iOffset only if
1.1329 +** a limit or offset is defined by pLimit and pOffset. iLimit and
1.1330 +** iOffset should have been preset to appropriate default values
1.1331 +** (usually but not always -1) prior to calling this routine.
1.1332 +** Only if pLimit!=0 or pOffset!=0 do the limit registers get
1.1333 +** redefined. The UNION ALL operator uses this property to force
1.1334 +** the reuse of the same limit and offset registers across multiple
1.1335 +** SELECT statements.
1.1336 +*/
1.1337 +static void computeLimitRegisters(Parse *pParse, Select *p, int iBreak){
1.1338 + Vdbe *v = 0;
1.1339 + int iLimit = 0;
1.1340 + int iOffset;
1.1341 + int addr1;
1.1342 + if( p->iLimit ) return;
1.1343 +
1.1344 + /*
1.1345 + ** "LIMIT -1" always shows all rows. There is some
1.1346 + ** contraversy about what the correct behavior should be.
1.1347 + ** The current implementation interprets "LIMIT 0" to mean
1.1348 + ** no rows.
1.1349 + */
1.1350 + if( p->pLimit ){
1.1351 + p->iLimit = iLimit = ++pParse->nMem;
1.1352 + v = sqlite3GetVdbe(pParse);
1.1353 + if( v==0 ) return;
1.1354 + sqlite3ExprCode(pParse, p->pLimit, iLimit);
1.1355 + sqlite3VdbeAddOp1(v, OP_MustBeInt, iLimit);
1.1356 + VdbeComment((v, "LIMIT counter"));
1.1357 + sqlite3VdbeAddOp2(v, OP_IfZero, iLimit, iBreak);
1.1358 + }
1.1359 + if( p->pOffset ){
1.1360 + p->iOffset = iOffset = ++pParse->nMem;
1.1361 + if( p->pLimit ){
1.1362 + pParse->nMem++; /* Allocate an extra register for limit+offset */
1.1363 + }
1.1364 + v = sqlite3GetVdbe(pParse);
1.1365 + if( v==0 ) return;
1.1366 + sqlite3ExprCode(pParse, p->pOffset, iOffset);
1.1367 + sqlite3VdbeAddOp1(v, OP_MustBeInt, iOffset);
1.1368 + VdbeComment((v, "OFFSET counter"));
1.1369 + addr1 = sqlite3VdbeAddOp1(v, OP_IfPos, iOffset);
1.1370 + sqlite3VdbeAddOp2(v, OP_Integer, 0, iOffset);
1.1371 + sqlite3VdbeJumpHere(v, addr1);
1.1372 + if( p->pLimit ){
1.1373 + sqlite3VdbeAddOp3(v, OP_Add, iLimit, iOffset, iOffset+1);
1.1374 + VdbeComment((v, "LIMIT+OFFSET"));
1.1375 + addr1 = sqlite3VdbeAddOp1(v, OP_IfPos, iLimit);
1.1376 + sqlite3VdbeAddOp2(v, OP_Integer, -1, iOffset+1);
1.1377 + sqlite3VdbeJumpHere(v, addr1);
1.1378 + }
1.1379 + }
1.1380 +}
1.1381 +
1.1382 +#ifndef SQLITE_OMIT_COMPOUND_SELECT
1.1383 +/*
1.1384 +** Return the appropriate collating sequence for the iCol-th column of
1.1385 +** the result set for the compound-select statement "p". Return NULL if
1.1386 +** the column has no default collating sequence.
1.1387 +**
1.1388 +** The collating sequence for the compound select is taken from the
1.1389 +** left-most term of the select that has a collating sequence.
1.1390 +*/
1.1391 +static CollSeq *multiSelectCollSeq(Parse *pParse, Select *p, int iCol){
1.1392 + CollSeq *pRet;
1.1393 + if( p->pPrior ){
1.1394 + pRet = multiSelectCollSeq(pParse, p->pPrior, iCol);
1.1395 + }else{
1.1396 + pRet = 0;
1.1397 + }
1.1398 + if( pRet==0 ){
1.1399 + pRet = sqlite3ExprCollSeq(pParse, p->pEList->a[iCol].pExpr);
1.1400 + }
1.1401 + return pRet;
1.1402 +}
1.1403 +#endif /* SQLITE_OMIT_COMPOUND_SELECT */
1.1404 +
1.1405 +/* Forward reference */
1.1406 +static int multiSelectOrderBy(
1.1407 + Parse *pParse, /* Parsing context */
1.1408 + Select *p, /* The right-most of SELECTs to be coded */
1.1409 + SelectDest *pDest /* What to do with query results */
1.1410 +);
1.1411 +
1.1412 +
1.1413 +#ifndef SQLITE_OMIT_COMPOUND_SELECT
1.1414 +/*
1.1415 +** This routine is called to process a compound query form from
1.1416 +** two or more separate queries using UNION, UNION ALL, EXCEPT, or
1.1417 +** INTERSECT
1.1418 +**
1.1419 +** "p" points to the right-most of the two queries. the query on the
1.1420 +** left is p->pPrior. The left query could also be a compound query
1.1421 +** in which case this routine will be called recursively.
1.1422 +**
1.1423 +** The results of the total query are to be written into a destination
1.1424 +** of type eDest with parameter iParm.
1.1425 +**
1.1426 +** Example 1: Consider a three-way compound SQL statement.
1.1427 +**
1.1428 +** SELECT a FROM t1 UNION SELECT b FROM t2 UNION SELECT c FROM t3
1.1429 +**
1.1430 +** This statement is parsed up as follows:
1.1431 +**
1.1432 +** SELECT c FROM t3
1.1433 +** |
1.1434 +** `-----> SELECT b FROM t2
1.1435 +** |
1.1436 +** `------> SELECT a FROM t1
1.1437 +**
1.1438 +** The arrows in the diagram above represent the Select.pPrior pointer.
1.1439 +** So if this routine is called with p equal to the t3 query, then
1.1440 +** pPrior will be the t2 query. p->op will be TK_UNION in this case.
1.1441 +**
1.1442 +** Notice that because of the way SQLite parses compound SELECTs, the
1.1443 +** individual selects always group from left to right.
1.1444 +*/
1.1445 +static int multiSelect(
1.1446 + Parse *pParse, /* Parsing context */
1.1447 + Select *p, /* The right-most of SELECTs to be coded */
1.1448 + SelectDest *pDest /* What to do with query results */
1.1449 +){
1.1450 + int rc = SQLITE_OK; /* Success code from a subroutine */
1.1451 + Select *pPrior; /* Another SELECT immediately to our left */
1.1452 + Vdbe *v; /* Generate code to this VDBE */
1.1453 + SelectDest dest; /* Alternative data destination */
1.1454 + Select *pDelete = 0; /* Chain of simple selects to delete */
1.1455 + sqlite3 *db; /* Database connection */
1.1456 +
1.1457 + /* Make sure there is no ORDER BY or LIMIT clause on prior SELECTs. Only
1.1458 + ** the last (right-most) SELECT in the series may have an ORDER BY or LIMIT.
1.1459 + */
1.1460 + assert( p && p->pPrior ); /* Calling function guarantees this much */
1.1461 + db = pParse->db;
1.1462 + pPrior = p->pPrior;
1.1463 + assert( pPrior->pRightmost!=pPrior );
1.1464 + assert( pPrior->pRightmost==p->pRightmost );
1.1465 + dest = *pDest;
1.1466 + if( pPrior->pOrderBy ){
1.1467 + sqlite3ErrorMsg(pParse,"ORDER BY clause should come after %s not before",
1.1468 + selectOpName(p->op));
1.1469 + rc = 1;
1.1470 + goto multi_select_end;
1.1471 + }
1.1472 + if( pPrior->pLimit ){
1.1473 + sqlite3ErrorMsg(pParse,"LIMIT clause should come after %s not before",
1.1474 + selectOpName(p->op));
1.1475 + rc = 1;
1.1476 + goto multi_select_end;
1.1477 + }
1.1478 +
1.1479 + v = sqlite3GetVdbe(pParse);
1.1480 + assert( v!=0 ); /* The VDBE already created by calling function */
1.1481 +
1.1482 + /* Create the destination temporary table if necessary
1.1483 + */
1.1484 + if( dest.eDest==SRT_EphemTab ){
1.1485 + assert( p->pEList );
1.1486 + sqlite3VdbeAddOp2(v, OP_OpenEphemeral, dest.iParm, p->pEList->nExpr);
1.1487 + dest.eDest = SRT_Table;
1.1488 + }
1.1489 +
1.1490 + /* Make sure all SELECTs in the statement have the same number of elements
1.1491 + ** in their result sets.
1.1492 + */
1.1493 + assert( p->pEList && pPrior->pEList );
1.1494 + if( p->pEList->nExpr!=pPrior->pEList->nExpr ){
1.1495 + sqlite3ErrorMsg(pParse, "SELECTs to the left and right of %s"
1.1496 + " do not have the same number of result columns", selectOpName(p->op));
1.1497 + rc = 1;
1.1498 + goto multi_select_end;
1.1499 + }
1.1500 +
1.1501 + /* Compound SELECTs that have an ORDER BY clause are handled separately.
1.1502 + */
1.1503 + if( p->pOrderBy ){
1.1504 + return multiSelectOrderBy(pParse, p, pDest);
1.1505 + }
1.1506 +
1.1507 + /* Generate code for the left and right SELECT statements.
1.1508 + */
1.1509 + switch( p->op ){
1.1510 + case TK_ALL: {
1.1511 + int addr = 0;
1.1512 + assert( !pPrior->pLimit );
1.1513 + pPrior->pLimit = p->pLimit;
1.1514 + pPrior->pOffset = p->pOffset;
1.1515 + rc = sqlite3Select(pParse, pPrior, &dest);
1.1516 + p->pLimit = 0;
1.1517 + p->pOffset = 0;
1.1518 + if( rc ){
1.1519 + goto multi_select_end;
1.1520 + }
1.1521 + p->pPrior = 0;
1.1522 + p->iLimit = pPrior->iLimit;
1.1523 + p->iOffset = pPrior->iOffset;
1.1524 + if( p->iLimit ){
1.1525 + addr = sqlite3VdbeAddOp1(v, OP_IfZero, p->iLimit);
1.1526 + VdbeComment((v, "Jump ahead if LIMIT reached"));
1.1527 + }
1.1528 + rc = sqlite3Select(pParse, p, &dest);
1.1529 + pDelete = p->pPrior;
1.1530 + p->pPrior = pPrior;
1.1531 + if( rc ){
1.1532 + goto multi_select_end;
1.1533 + }
1.1534 + if( addr ){
1.1535 + sqlite3VdbeJumpHere(v, addr);
1.1536 + }
1.1537 + break;
1.1538 + }
1.1539 + case TK_EXCEPT:
1.1540 + case TK_UNION: {
1.1541 + int unionTab; /* Cursor number of the temporary table holding result */
1.1542 + int op = 0; /* One of the SRT_ operations to apply to self */
1.1543 + int priorOp; /* The SRT_ operation to apply to prior selects */
1.1544 + Expr *pLimit, *pOffset; /* Saved values of p->nLimit and p->nOffset */
1.1545 + int addr;
1.1546 + SelectDest uniondest;
1.1547 +
1.1548 + priorOp = SRT_Union;
1.1549 + if( dest.eDest==priorOp && !p->pLimit && !p->pOffset ){
1.1550 + /* We can reuse a temporary table generated by a SELECT to our
1.1551 + ** right.
1.1552 + */
1.1553 + unionTab = dest.iParm;
1.1554 + }else{
1.1555 + /* We will need to create our own temporary table to hold the
1.1556 + ** intermediate results.
1.1557 + */
1.1558 + unionTab = pParse->nTab++;
1.1559 + assert( p->pOrderBy==0 );
1.1560 + addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, unionTab, 0);
1.1561 + assert( p->addrOpenEphm[0] == -1 );
1.1562 + p->addrOpenEphm[0] = addr;
1.1563 + p->pRightmost->selFlags |= SF_UsesEphemeral;
1.1564 + assert( p->pEList );
1.1565 + }
1.1566 +
1.1567 + /* Code the SELECT statements to our left
1.1568 + */
1.1569 + assert( !pPrior->pOrderBy );
1.1570 + sqlite3SelectDestInit(&uniondest, priorOp, unionTab);
1.1571 + rc = sqlite3Select(pParse, pPrior, &uniondest);
1.1572 + if( rc ){
1.1573 + goto multi_select_end;
1.1574 + }
1.1575 +
1.1576 + /* Code the current SELECT statement
1.1577 + */
1.1578 + if( p->op==TK_EXCEPT ){
1.1579 + op = SRT_Except;
1.1580 + }else{
1.1581 + assert( p->op==TK_UNION );
1.1582 + op = SRT_Union;
1.1583 + }
1.1584 + p->pPrior = 0;
1.1585 + pLimit = p->pLimit;
1.1586 + p->pLimit = 0;
1.1587 + pOffset = p->pOffset;
1.1588 + p->pOffset = 0;
1.1589 + uniondest.eDest = op;
1.1590 + rc = sqlite3Select(pParse, p, &uniondest);
1.1591 + /* Query flattening in sqlite3Select() might refill p->pOrderBy.
1.1592 + ** Be sure to delete p->pOrderBy, therefore, to avoid a memory leak. */
1.1593 + sqlite3ExprListDelete(db, p->pOrderBy);
1.1594 + pDelete = p->pPrior;
1.1595 + p->pPrior = pPrior;
1.1596 + p->pOrderBy = 0;
1.1597 + sqlite3ExprDelete(db, p->pLimit);
1.1598 + p->pLimit = pLimit;
1.1599 + p->pOffset = pOffset;
1.1600 + p->iLimit = 0;
1.1601 + p->iOffset = 0;
1.1602 + if( rc ){
1.1603 + goto multi_select_end;
1.1604 + }
1.1605 +
1.1606 +
1.1607 + /* Convert the data in the temporary table into whatever form
1.1608 + ** it is that we currently need.
1.1609 + */
1.1610 + if( dest.eDest!=priorOp || unionTab!=dest.iParm ){
1.1611 + int iCont, iBreak, iStart;
1.1612 + assert( p->pEList );
1.1613 + if( dest.eDest==SRT_Output ){
1.1614 + Select *pFirst = p;
1.1615 + while( pFirst->pPrior ) pFirst = pFirst->pPrior;
1.1616 + generateColumnNames(pParse, 0, pFirst->pEList);
1.1617 + }
1.1618 + iBreak = sqlite3VdbeMakeLabel(v);
1.1619 + iCont = sqlite3VdbeMakeLabel(v);
1.1620 + computeLimitRegisters(pParse, p, iBreak);
1.1621 + sqlite3VdbeAddOp2(v, OP_Rewind, unionTab, iBreak);
1.1622 + iStart = sqlite3VdbeCurrentAddr(v);
1.1623 + selectInnerLoop(pParse, p, p->pEList, unionTab, p->pEList->nExpr,
1.1624 + 0, -1, &dest, iCont, iBreak);
1.1625 + sqlite3VdbeResolveLabel(v, iCont);
1.1626 + sqlite3VdbeAddOp2(v, OP_Next, unionTab, iStart);
1.1627 + sqlite3VdbeResolveLabel(v, iBreak);
1.1628 + sqlite3VdbeAddOp2(v, OP_Close, unionTab, 0);
1.1629 + }
1.1630 + break;
1.1631 + }
1.1632 + case TK_INTERSECT: {
1.1633 + int tab1, tab2;
1.1634 + int iCont, iBreak, iStart;
1.1635 + Expr *pLimit, *pOffset;
1.1636 + int addr;
1.1637 + SelectDest intersectdest;
1.1638 + int r1;
1.1639 +
1.1640 + /* INTERSECT is different from the others since it requires
1.1641 + ** two temporary tables. Hence it has its own case. Begin
1.1642 + ** by allocating the tables we will need.
1.1643 + */
1.1644 + tab1 = pParse->nTab++;
1.1645 + tab2 = pParse->nTab++;
1.1646 + assert( p->pOrderBy==0 );
1.1647 +
1.1648 + addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tab1, 0);
1.1649 + assert( p->addrOpenEphm[0] == -1 );
1.1650 + p->addrOpenEphm[0] = addr;
1.1651 + p->pRightmost->selFlags |= SF_UsesEphemeral;
1.1652 + assert( p->pEList );
1.1653 +
1.1654 + /* Code the SELECTs to our left into temporary table "tab1".
1.1655 + */
1.1656 + sqlite3SelectDestInit(&intersectdest, SRT_Union, tab1);
1.1657 + rc = sqlite3Select(pParse, pPrior, &intersectdest);
1.1658 + if( rc ){
1.1659 + goto multi_select_end;
1.1660 + }
1.1661 +
1.1662 + /* Code the current SELECT into temporary table "tab2"
1.1663 + */
1.1664 + addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tab2, 0);
1.1665 + assert( p->addrOpenEphm[1] == -1 );
1.1666 + p->addrOpenEphm[1] = addr;
1.1667 + p->pPrior = 0;
1.1668 + pLimit = p->pLimit;
1.1669 + p->pLimit = 0;
1.1670 + pOffset = p->pOffset;
1.1671 + p->pOffset = 0;
1.1672 + intersectdest.iParm = tab2;
1.1673 + rc = sqlite3Select(pParse, p, &intersectdest);
1.1674 + pDelete = p->pPrior;
1.1675 + p->pPrior = pPrior;
1.1676 + sqlite3ExprDelete(db, p->pLimit);
1.1677 + p->pLimit = pLimit;
1.1678 + p->pOffset = pOffset;
1.1679 + if( rc ){
1.1680 + goto multi_select_end;
1.1681 + }
1.1682 +
1.1683 + /* Generate code to take the intersection of the two temporary
1.1684 + ** tables.
1.1685 + */
1.1686 + assert( p->pEList );
1.1687 + if( dest.eDest==SRT_Output ){
1.1688 + Select *pFirst = p;
1.1689 + while( pFirst->pPrior ) pFirst = pFirst->pPrior;
1.1690 + generateColumnNames(pParse, 0, pFirst->pEList);
1.1691 + }
1.1692 + iBreak = sqlite3VdbeMakeLabel(v);
1.1693 + iCont = sqlite3VdbeMakeLabel(v);
1.1694 + computeLimitRegisters(pParse, p, iBreak);
1.1695 + sqlite3VdbeAddOp2(v, OP_Rewind, tab1, iBreak);
1.1696 + r1 = sqlite3GetTempReg(pParse);
1.1697 + iStart = sqlite3VdbeAddOp2(v, OP_RowKey, tab1, r1);
1.1698 + sqlite3VdbeAddOp3(v, OP_NotFound, tab2, iCont, r1);
1.1699 + sqlite3ReleaseTempReg(pParse, r1);
1.1700 + selectInnerLoop(pParse, p, p->pEList, tab1, p->pEList->nExpr,
1.1701 + 0, -1, &dest, iCont, iBreak);
1.1702 + sqlite3VdbeResolveLabel(v, iCont);
1.1703 + sqlite3VdbeAddOp2(v, OP_Next, tab1, iStart);
1.1704 + sqlite3VdbeResolveLabel(v, iBreak);
1.1705 + sqlite3VdbeAddOp2(v, OP_Close, tab2, 0);
1.1706 + sqlite3VdbeAddOp2(v, OP_Close, tab1, 0);
1.1707 + break;
1.1708 + }
1.1709 + }
1.1710 +
1.1711 + /* Compute collating sequences used by
1.1712 + ** temporary tables needed to implement the compound select.
1.1713 + ** Attach the KeyInfo structure to all temporary tables.
1.1714 + **
1.1715 + ** This section is run by the right-most SELECT statement only.
1.1716 + ** SELECT statements to the left always skip this part. The right-most
1.1717 + ** SELECT might also skip this part if it has no ORDER BY clause and
1.1718 + ** no temp tables are required.
1.1719 + */
1.1720 + if( p->selFlags & SF_UsesEphemeral ){
1.1721 + int i; /* Loop counter */
1.1722 + KeyInfo *pKeyInfo; /* Collating sequence for the result set */
1.1723 + Select *pLoop; /* For looping through SELECT statements */
1.1724 + CollSeq **apColl; /* For looping through pKeyInfo->aColl[] */
1.1725 + int nCol; /* Number of columns in result set */
1.1726 +
1.1727 + assert( p->pRightmost==p );
1.1728 + nCol = p->pEList->nExpr;
1.1729 + pKeyInfo = sqlite3DbMallocZero(db,
1.1730 + sizeof(*pKeyInfo)+nCol*(sizeof(CollSeq*) + 1));
1.1731 + if( !pKeyInfo ){
1.1732 + rc = SQLITE_NOMEM;
1.1733 + goto multi_select_end;
1.1734 + }
1.1735 +
1.1736 + pKeyInfo->enc = ENC(db);
1.1737 + pKeyInfo->nField = nCol;
1.1738 +
1.1739 + for(i=0, apColl=pKeyInfo->aColl; i<nCol; i++, apColl++){
1.1740 + *apColl = multiSelectCollSeq(pParse, p, i);
1.1741 + if( 0==*apColl ){
1.1742 + *apColl = db->pDfltColl;
1.1743 + }
1.1744 + }
1.1745 +
1.1746 + for(pLoop=p; pLoop; pLoop=pLoop->pPrior){
1.1747 + for(i=0; i<2; i++){
1.1748 + int addr = pLoop->addrOpenEphm[i];
1.1749 + if( addr<0 ){
1.1750 + /* If [0] is unused then [1] is also unused. So we can
1.1751 + ** always safely abort as soon as the first unused slot is found */
1.1752 + assert( pLoop->addrOpenEphm[1]<0 );
1.1753 + break;
1.1754 + }
1.1755 + sqlite3VdbeChangeP2(v, addr, nCol);
1.1756 + sqlite3VdbeChangeP4(v, addr, (char*)pKeyInfo, P4_KEYINFO);
1.1757 + pLoop->addrOpenEphm[i] = -1;
1.1758 + }
1.1759 + }
1.1760 + sqlite3DbFree(db, pKeyInfo);
1.1761 + }
1.1762 +
1.1763 +multi_select_end:
1.1764 + pDest->iMem = dest.iMem;
1.1765 + pDest->nMem = dest.nMem;
1.1766 + sqlite3SelectDelete(db, pDelete);
1.1767 + return rc;
1.1768 +}
1.1769 +#endif /* SQLITE_OMIT_COMPOUND_SELECT */
1.1770 +
1.1771 +/*
1.1772 +** Code an output subroutine for a coroutine implementation of a
1.1773 +** SELECT statment.
1.1774 +**
1.1775 +** The data to be output is contained in pIn->iMem. There are
1.1776 +** pIn->nMem columns to be output. pDest is where the output should
1.1777 +** be sent.
1.1778 +**
1.1779 +** regReturn is the number of the register holding the subroutine
1.1780 +** return address.
1.1781 +**
1.1782 +** If regPrev>0 then it is a the first register in a vector that
1.1783 +** records the previous output. mem[regPrev] is a flag that is false
1.1784 +** if there has been no previous output. If regPrev>0 then code is
1.1785 +** generated to suppress duplicates. pKeyInfo is used for comparing
1.1786 +** keys.
1.1787 +**
1.1788 +** If the LIMIT found in p->iLimit is reached, jump immediately to
1.1789 +** iBreak.
1.1790 +*/
1.1791 +static int generateOutputSubroutine(
1.1792 + Parse *pParse, /* Parsing context */
1.1793 + Select *p, /* The SELECT statement */
1.1794 + SelectDest *pIn, /* Coroutine supplying data */
1.1795 + SelectDest *pDest, /* Where to send the data */
1.1796 + int regReturn, /* The return address register */
1.1797 + int regPrev, /* Previous result register. No uniqueness if 0 */
1.1798 + KeyInfo *pKeyInfo, /* For comparing with previous entry */
1.1799 + int p4type, /* The p4 type for pKeyInfo */
1.1800 + int iBreak /* Jump here if we hit the LIMIT */
1.1801 +){
1.1802 + Vdbe *v = pParse->pVdbe;
1.1803 + int iContinue;
1.1804 + int addr;
1.1805 +
1.1806 + addr = sqlite3VdbeCurrentAddr(v);
1.1807 + iContinue = sqlite3VdbeMakeLabel(v);
1.1808 +
1.1809 + /* Suppress duplicates for UNION, EXCEPT, and INTERSECT
1.1810 + */
1.1811 + if( regPrev ){
1.1812 + int j1, j2;
1.1813 + j1 = sqlite3VdbeAddOp1(v, OP_IfNot, regPrev);
1.1814 + j2 = sqlite3VdbeAddOp4(v, OP_Compare, pIn->iMem, regPrev+1, pIn->nMem,
1.1815 + (char*)pKeyInfo, p4type);
1.1816 + sqlite3VdbeAddOp3(v, OP_Jump, j2+2, iContinue, j2+2);
1.1817 + sqlite3VdbeJumpHere(v, j1);
1.1818 + sqlite3ExprCodeCopy(pParse, pIn->iMem, regPrev+1, pIn->nMem);
1.1819 + sqlite3VdbeAddOp2(v, OP_Integer, 1, regPrev);
1.1820 + }
1.1821 + if( pParse->db->mallocFailed ) return 0;
1.1822 +
1.1823 + /* Suppress the the first OFFSET entries if there is an OFFSET clause
1.1824 + */
1.1825 + codeOffset(v, p, iContinue);
1.1826 +
1.1827 + switch( pDest->eDest ){
1.1828 + /* Store the result as data using a unique key.
1.1829 + */
1.1830 + case SRT_Table:
1.1831 + case SRT_EphemTab: {
1.1832 + int r1 = sqlite3GetTempReg(pParse);
1.1833 + int r2 = sqlite3GetTempReg(pParse);
1.1834 + sqlite3VdbeAddOp3(v, OP_MakeRecord, pIn->iMem, pIn->nMem, r1);
1.1835 + sqlite3VdbeAddOp2(v, OP_NewRowid, pDest->iParm, r2);
1.1836 + sqlite3VdbeAddOp3(v, OP_Insert, pDest->iParm, r1, r2);
1.1837 + sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
1.1838 + sqlite3ReleaseTempReg(pParse, r2);
1.1839 + sqlite3ReleaseTempReg(pParse, r1);
1.1840 + break;
1.1841 + }
1.1842 +
1.1843 +#ifndef SQLITE_OMIT_SUBQUERY
1.1844 + /* If we are creating a set for an "expr IN (SELECT ...)" construct,
1.1845 + ** then there should be a single item on the stack. Write this
1.1846 + ** item into the set table with bogus data.
1.1847 + */
1.1848 + case SRT_Set: {
1.1849 + int r1;
1.1850 + assert( pIn->nMem==1 );
1.1851 + p->affinity =
1.1852 + sqlite3CompareAffinity(p->pEList->a[0].pExpr, pDest->affinity);
1.1853 + r1 = sqlite3GetTempReg(pParse);
1.1854 + sqlite3VdbeAddOp4(v, OP_MakeRecord, pIn->iMem, 1, r1, &p->affinity, 1);
1.1855 + sqlite3ExprCacheAffinityChange(pParse, pIn->iMem, 1);
1.1856 + sqlite3VdbeAddOp2(v, OP_IdxInsert, pDest->iParm, r1);
1.1857 + sqlite3ReleaseTempReg(pParse, r1);
1.1858 + break;
1.1859 + }
1.1860 +
1.1861 +#if 0 /* Never occurs on an ORDER BY query */
1.1862 + /* If any row exist in the result set, record that fact and abort.
1.1863 + */
1.1864 + case SRT_Exists: {
1.1865 + sqlite3VdbeAddOp2(v, OP_Integer, 1, pDest->iParm);
1.1866 + /* The LIMIT clause will terminate the loop for us */
1.1867 + break;
1.1868 + }
1.1869 +#endif
1.1870 +
1.1871 + /* If this is a scalar select that is part of an expression, then
1.1872 + ** store the results in the appropriate memory cell and break out
1.1873 + ** of the scan loop.
1.1874 + */
1.1875 + case SRT_Mem: {
1.1876 + assert( pIn->nMem==1 );
1.1877 + sqlite3ExprCodeMove(pParse, pIn->iMem, pDest->iParm, 1);
1.1878 + /* The LIMIT clause will jump out of the loop for us */
1.1879 + break;
1.1880 + }
1.1881 +#endif /* #ifndef SQLITE_OMIT_SUBQUERY */
1.1882 +
1.1883 + /* The results are stored in a sequence of registers
1.1884 + ** starting at pDest->iMem. Then the co-routine yields.
1.1885 + */
1.1886 + case SRT_Coroutine: {
1.1887 + if( pDest->iMem==0 ){
1.1888 + pDest->iMem = sqlite3GetTempRange(pParse, pIn->nMem);
1.1889 + pDest->nMem = pIn->nMem;
1.1890 + }
1.1891 + sqlite3ExprCodeMove(pParse, pIn->iMem, pDest->iMem, pDest->nMem);
1.1892 + sqlite3VdbeAddOp1(v, OP_Yield, pDest->iParm);
1.1893 + break;
1.1894 + }
1.1895 +
1.1896 + /* Results are stored in a sequence of registers. Then the
1.1897 + ** OP_ResultRow opcode is used to cause sqlite3_step() to return
1.1898 + ** the next row of result.
1.1899 + */
1.1900 + case SRT_Output: {
1.1901 + sqlite3VdbeAddOp2(v, OP_ResultRow, pIn->iMem, pIn->nMem);
1.1902 + sqlite3ExprCacheAffinityChange(pParse, pIn->iMem, pIn->nMem);
1.1903 + break;
1.1904 + }
1.1905 +
1.1906 +#if !defined(SQLITE_OMIT_TRIGGER)
1.1907 + /* Discard the results. This is used for SELECT statements inside
1.1908 + ** the body of a TRIGGER. The purpose of such selects is to call
1.1909 + ** user-defined functions that have side effects. We do not care
1.1910 + ** about the actual results of the select.
1.1911 + */
1.1912 + default: {
1.1913 + break;
1.1914 + }
1.1915 +#endif
1.1916 + }
1.1917 +
1.1918 + /* Jump to the end of the loop if the LIMIT is reached.
1.1919 + */
1.1920 + if( p->iLimit ){
1.1921 + sqlite3VdbeAddOp2(v, OP_AddImm, p->iLimit, -1);
1.1922 + sqlite3VdbeAddOp2(v, OP_IfZero, p->iLimit, iBreak);
1.1923 + }
1.1924 +
1.1925 + /* Generate the subroutine return
1.1926 + */
1.1927 + sqlite3VdbeResolveLabel(v, iContinue);
1.1928 + sqlite3VdbeAddOp1(v, OP_Return, regReturn);
1.1929 +
1.1930 + return addr;
1.1931 +}
1.1932 +
1.1933 +/*
1.1934 +** Alternative compound select code generator for cases when there
1.1935 +** is an ORDER BY clause.
1.1936 +**
1.1937 +** We assume a query of the following form:
1.1938 +**
1.1939 +** <selectA> <operator> <selectB> ORDER BY <orderbylist>
1.1940 +**
1.1941 +** <operator> is one of UNION ALL, UNION, EXCEPT, or INTERSECT. The idea
1.1942 +** is to code both <selectA> and <selectB> with the ORDER BY clause as
1.1943 +** co-routines. Then run the co-routines in parallel and merge the results
1.1944 +** into the output. In addition to the two coroutines (called selectA and
1.1945 +** selectB) there are 7 subroutines:
1.1946 +**
1.1947 +** outA: Move the output of the selectA coroutine into the output
1.1948 +** of the compound query.
1.1949 +**
1.1950 +** outB: Move the output of the selectB coroutine into the output
1.1951 +** of the compound query. (Only generated for UNION and
1.1952 +** UNION ALL. EXCEPT and INSERTSECT never output a row that
1.1953 +** appears only in B.)
1.1954 +**
1.1955 +** AltB: Called when there is data from both coroutines and A<B.
1.1956 +**
1.1957 +** AeqB: Called when there is data from both coroutines and A==B.
1.1958 +**
1.1959 +** AgtB: Called when there is data from both coroutines and A>B.
1.1960 +**
1.1961 +** EofA: Called when data is exhausted from selectA.
1.1962 +**
1.1963 +** EofB: Called when data is exhausted from selectB.
1.1964 +**
1.1965 +** The implementation of the latter five subroutines depend on which
1.1966 +** <operator> is used:
1.1967 +**
1.1968 +**
1.1969 +** UNION ALL UNION EXCEPT INTERSECT
1.1970 +** ------------- ----------------- -------------- -----------------
1.1971 +** AltB: outA, nextA outA, nextA outA, nextA nextA
1.1972 +**
1.1973 +** AeqB: outA, nextA nextA nextA outA, nextA
1.1974 +**
1.1975 +** AgtB: outB, nextB outB, nextB nextB nextB
1.1976 +**
1.1977 +** EofA: outB, nextB outB, nextB halt halt
1.1978 +**
1.1979 +** EofB: outA, nextA outA, nextA outA, nextA halt
1.1980 +**
1.1981 +** In the AltB, AeqB, and AgtB subroutines, an EOF on A following nextA
1.1982 +** causes an immediate jump to EofA and an EOF on B following nextB causes
1.1983 +** an immediate jump to EofB. Within EofA and EofB, and EOF on entry or
1.1984 +** following nextX causes a jump to the end of the select processing.
1.1985 +**
1.1986 +** Duplicate removal in the UNION, EXCEPT, and INTERSECT cases is handled
1.1987 +** within the output subroutine. The regPrev register set holds the previously
1.1988 +** output value. A comparison is made against this value and the output
1.1989 +** is skipped if the next results would be the same as the previous.
1.1990 +**
1.1991 +** The implementation plan is to implement the two coroutines and seven
1.1992 +** subroutines first, then put the control logic at the bottom. Like this:
1.1993 +**
1.1994 +** goto Init
1.1995 +** coA: coroutine for left query (A)
1.1996 +** coB: coroutine for right query (B)
1.1997 +** outA: output one row of A
1.1998 +** outB: output one row of B (UNION and UNION ALL only)
1.1999 +** EofA: ...
1.2000 +** EofB: ...
1.2001 +** AltB: ...
1.2002 +** AeqB: ...
1.2003 +** AgtB: ...
1.2004 +** Init: initialize coroutine registers
1.2005 +** yield coA
1.2006 +** if eof(A) goto EofA
1.2007 +** yield coB
1.2008 +** if eof(B) goto EofB
1.2009 +** Cmpr: Compare A, B
1.2010 +** Jump AltB, AeqB, AgtB
1.2011 +** End: ...
1.2012 +**
1.2013 +** We call AltB, AeqB, AgtB, EofA, and EofB "subroutines" but they are not
1.2014 +** actually called using Gosub and they do not Return. EofA and EofB loop
1.2015 +** until all data is exhausted then jump to the "end" labe. AltB, AeqB,
1.2016 +** and AgtB jump to either L2 or to one of EofA or EofB.
1.2017 +*/
1.2018 +#ifndef SQLITE_OMIT_COMPOUND_SELECT
1.2019 +static int multiSelectOrderBy(
1.2020 + Parse *pParse, /* Parsing context */
1.2021 + Select *p, /* The right-most of SELECTs to be coded */
1.2022 + SelectDest *pDest /* What to do with query results */
1.2023 +){
1.2024 + int i, j; /* Loop counters */
1.2025 + Select *pPrior; /* Another SELECT immediately to our left */
1.2026 + Vdbe *v; /* Generate code to this VDBE */
1.2027 + SelectDest destA; /* Destination for coroutine A */
1.2028 + SelectDest destB; /* Destination for coroutine B */
1.2029 + int regAddrA; /* Address register for select-A coroutine */
1.2030 + int regEofA; /* Flag to indicate when select-A is complete */
1.2031 + int regAddrB; /* Address register for select-B coroutine */
1.2032 + int regEofB; /* Flag to indicate when select-B is complete */
1.2033 + int addrSelectA; /* Address of the select-A coroutine */
1.2034 + int addrSelectB; /* Address of the select-B coroutine */
1.2035 + int regOutA; /* Address register for the output-A subroutine */
1.2036 + int regOutB; /* Address register for the output-B subroutine */
1.2037 + int addrOutA; /* Address of the output-A subroutine */
1.2038 + int addrOutB; /* Address of the output-B subroutine */
1.2039 + int addrEofA; /* Address of the select-A-exhausted subroutine */
1.2040 + int addrEofB; /* Address of the select-B-exhausted subroutine */
1.2041 + int addrAltB; /* Address of the A<B subroutine */
1.2042 + int addrAeqB; /* Address of the A==B subroutine */
1.2043 + int addrAgtB; /* Address of the A>B subroutine */
1.2044 + int regLimitA; /* Limit register for select-A */
1.2045 + int regLimitB; /* Limit register for select-A */
1.2046 + int regPrev; /* A range of registers to hold previous output */
1.2047 + int savedLimit; /* Saved value of p->iLimit */
1.2048 + int savedOffset; /* Saved value of p->iOffset */
1.2049 + int labelCmpr; /* Label for the start of the merge algorithm */
1.2050 + int labelEnd; /* Label for the end of the overall SELECT stmt */
1.2051 + int j1; /* Jump instructions that get retargetted */
1.2052 + int op; /* One of TK_ALL, TK_UNION, TK_EXCEPT, TK_INTERSECT */
1.2053 + KeyInfo *pKeyDup = 0; /* Comparison information for duplicate removal */
1.2054 + KeyInfo *pKeyMerge; /* Comparison information for merging rows */
1.2055 + sqlite3 *db; /* Database connection */
1.2056 + ExprList *pOrderBy; /* The ORDER BY clause */
1.2057 + int nOrderBy; /* Number of terms in the ORDER BY clause */
1.2058 + int *aPermute; /* Mapping from ORDER BY terms to result set columns */
1.2059 +
1.2060 + assert( p->pOrderBy!=0 );
1.2061 + assert( pKeyDup==0 ); /* "Managed" code needs this. Ticket #3382. */
1.2062 + db = pParse->db;
1.2063 + v = pParse->pVdbe;
1.2064 + if( v==0 ) return SQLITE_NOMEM;
1.2065 + labelEnd = sqlite3VdbeMakeLabel(v);
1.2066 + labelCmpr = sqlite3VdbeMakeLabel(v);
1.2067 +
1.2068 +
1.2069 + /* Patch up the ORDER BY clause
1.2070 + */
1.2071 + op = p->op;
1.2072 + pPrior = p->pPrior;
1.2073 + assert( pPrior->pOrderBy==0 );
1.2074 + pOrderBy = p->pOrderBy;
1.2075 + assert( pOrderBy );
1.2076 + nOrderBy = pOrderBy->nExpr;
1.2077 +
1.2078 + /* For operators other than UNION ALL we have to make sure that
1.2079 + ** the ORDER BY clause covers every term of the result set. Add
1.2080 + ** terms to the ORDER BY clause as necessary.
1.2081 + */
1.2082 + if( op!=TK_ALL ){
1.2083 + for(i=1; db->mallocFailed==0 && i<=p->pEList->nExpr; i++){
1.2084 + struct ExprList_item *pItem;
1.2085 + for(j=0, pItem=pOrderBy->a; j<nOrderBy; j++, pItem++){
1.2086 + assert( pItem->iCol>0 );
1.2087 + if( pItem->iCol==i ) break;
1.2088 + }
1.2089 + if( j==nOrderBy ){
1.2090 + Expr *pNew = sqlite3PExpr(pParse, TK_INTEGER, 0, 0, 0);
1.2091 + if( pNew==0 ) return SQLITE_NOMEM;
1.2092 + pNew->flags |= EP_IntValue;
1.2093 + pNew->iTable = i;
1.2094 + pOrderBy = sqlite3ExprListAppend(pParse, pOrderBy, pNew, 0);
1.2095 + pOrderBy->a[nOrderBy++].iCol = i;
1.2096 + }
1.2097 + }
1.2098 + }
1.2099 +
1.2100 + /* Compute the comparison permutation and keyinfo that is used with
1.2101 + ** the permutation in order to comparisons to determine if the next
1.2102 + ** row of results comes from selectA or selectB. Also add explicit
1.2103 + ** collations to the ORDER BY clause terms so that when the subqueries
1.2104 + ** to the right and the left are evaluated, they use the correct
1.2105 + ** collation.
1.2106 + */
1.2107 + aPermute = sqlite3DbMallocRaw(db, sizeof(int)*nOrderBy);
1.2108 + if( aPermute ){
1.2109 + struct ExprList_item *pItem;
1.2110 + for(i=0, pItem=pOrderBy->a; i<nOrderBy; i++, pItem++){
1.2111 + assert( pItem->iCol>0 && pItem->iCol<=p->pEList->nExpr );
1.2112 + aPermute[i] = pItem->iCol - 1;
1.2113 + }
1.2114 + pKeyMerge =
1.2115 + sqlite3DbMallocRaw(db, sizeof(*pKeyMerge)+nOrderBy*(sizeof(CollSeq*)+1));
1.2116 + if( pKeyMerge ){
1.2117 + pKeyMerge->aSortOrder = (u8*)&pKeyMerge->aColl[nOrderBy];
1.2118 + pKeyMerge->nField = nOrderBy;
1.2119 + pKeyMerge->enc = ENC(db);
1.2120 + for(i=0; i<nOrderBy; i++){
1.2121 + CollSeq *pColl;
1.2122 + Expr *pTerm = pOrderBy->a[i].pExpr;
1.2123 + if( pTerm->flags & EP_ExpCollate ){
1.2124 + pColl = pTerm->pColl;
1.2125 + }else{
1.2126 + pColl = multiSelectCollSeq(pParse, p, aPermute[i]);
1.2127 + pTerm->flags |= EP_ExpCollate;
1.2128 + pTerm->pColl = pColl;
1.2129 + }
1.2130 + pKeyMerge->aColl[i] = pColl;
1.2131 + pKeyMerge->aSortOrder[i] = pOrderBy->a[i].sortOrder;
1.2132 + }
1.2133 + }
1.2134 + }else{
1.2135 + pKeyMerge = 0;
1.2136 + }
1.2137 +
1.2138 + /* Reattach the ORDER BY clause to the query.
1.2139 + */
1.2140 + p->pOrderBy = pOrderBy;
1.2141 + pPrior->pOrderBy = sqlite3ExprListDup(pParse->db, pOrderBy);
1.2142 +
1.2143 + /* Allocate a range of temporary registers and the KeyInfo needed
1.2144 + ** for the logic that removes duplicate result rows when the
1.2145 + ** operator is UNION, EXCEPT, or INTERSECT (but not UNION ALL).
1.2146 + */
1.2147 + if( op==TK_ALL ){
1.2148 + regPrev = 0;
1.2149 + }else{
1.2150 + int nExpr = p->pEList->nExpr;
1.2151 + assert( nOrderBy>=nExpr );
1.2152 + regPrev = sqlite3GetTempRange(pParse, nExpr+1);
1.2153 + sqlite3VdbeAddOp2(v, OP_Integer, 0, regPrev);
1.2154 + pKeyDup = sqlite3DbMallocZero(db,
1.2155 + sizeof(*pKeyDup) + nExpr*(sizeof(CollSeq*)+1) );
1.2156 + if( pKeyDup ){
1.2157 + pKeyDup->aSortOrder = (u8*)&pKeyDup->aColl[nExpr];
1.2158 + pKeyDup->nField = nExpr;
1.2159 + pKeyDup->enc = ENC(db);
1.2160 + for(i=0; i<nExpr; i++){
1.2161 + pKeyDup->aColl[i] = multiSelectCollSeq(pParse, p, i);
1.2162 + pKeyDup->aSortOrder[i] = 0;
1.2163 + }
1.2164 + }
1.2165 + }
1.2166 +
1.2167 + /* Separate the left and the right query from one another
1.2168 + */
1.2169 + p->pPrior = 0;
1.2170 + pPrior->pRightmost = 0;
1.2171 + sqlite3ResolveOrderGroupBy(pParse, p, p->pOrderBy, "ORDER");
1.2172 + if( pPrior->pPrior==0 ){
1.2173 + sqlite3ResolveOrderGroupBy(pParse, pPrior, pPrior->pOrderBy, "ORDER");
1.2174 + }
1.2175 +
1.2176 + /* Compute the limit registers */
1.2177 + computeLimitRegisters(pParse, p, labelEnd);
1.2178 + if( p->iLimit && op==TK_ALL ){
1.2179 + regLimitA = ++pParse->nMem;
1.2180 + regLimitB = ++pParse->nMem;
1.2181 + sqlite3VdbeAddOp2(v, OP_Copy, p->iOffset ? p->iOffset+1 : p->iLimit,
1.2182 + regLimitA);
1.2183 + sqlite3VdbeAddOp2(v, OP_Copy, regLimitA, regLimitB);
1.2184 + }else{
1.2185 + regLimitA = regLimitB = 0;
1.2186 + }
1.2187 + sqlite3ExprDelete(db, p->pLimit);
1.2188 + p->pLimit = 0;
1.2189 + sqlite3ExprDelete(db, p->pOffset);
1.2190 + p->pOffset = 0;
1.2191 +
1.2192 + regAddrA = ++pParse->nMem;
1.2193 + regEofA = ++pParse->nMem;
1.2194 + regAddrB = ++pParse->nMem;
1.2195 + regEofB = ++pParse->nMem;
1.2196 + regOutA = ++pParse->nMem;
1.2197 + regOutB = ++pParse->nMem;
1.2198 + sqlite3SelectDestInit(&destA, SRT_Coroutine, regAddrA);
1.2199 + sqlite3SelectDestInit(&destB, SRT_Coroutine, regAddrB);
1.2200 +
1.2201 + /* Jump past the various subroutines and coroutines to the main
1.2202 + ** merge loop
1.2203 + */
1.2204 + j1 = sqlite3VdbeAddOp0(v, OP_Goto);
1.2205 + addrSelectA = sqlite3VdbeCurrentAddr(v);
1.2206 +
1.2207 +
1.2208 + /* Generate a coroutine to evaluate the SELECT statement to the
1.2209 + ** left of the compound operator - the "A" select.
1.2210 + */
1.2211 + VdbeNoopComment((v, "Begin coroutine for left SELECT"));
1.2212 + pPrior->iLimit = regLimitA;
1.2213 + sqlite3Select(pParse, pPrior, &destA);
1.2214 + sqlite3VdbeAddOp2(v, OP_Integer, 1, regEofA);
1.2215 + sqlite3VdbeAddOp1(v, OP_Yield, regAddrA);
1.2216 + VdbeNoopComment((v, "End coroutine for left SELECT"));
1.2217 +
1.2218 + /* Generate a coroutine to evaluate the SELECT statement on
1.2219 + ** the right - the "B" select
1.2220 + */
1.2221 + addrSelectB = sqlite3VdbeCurrentAddr(v);
1.2222 + VdbeNoopComment((v, "Begin coroutine for right SELECT"));
1.2223 + savedLimit = p->iLimit;
1.2224 + savedOffset = p->iOffset;
1.2225 + p->iLimit = regLimitB;
1.2226 + p->iOffset = 0;
1.2227 + sqlite3Select(pParse, p, &destB);
1.2228 + p->iLimit = savedLimit;
1.2229 + p->iOffset = savedOffset;
1.2230 + sqlite3VdbeAddOp2(v, OP_Integer, 1, regEofB);
1.2231 + sqlite3VdbeAddOp1(v, OP_Yield, regAddrB);
1.2232 + VdbeNoopComment((v, "End coroutine for right SELECT"));
1.2233 +
1.2234 + /* Generate a subroutine that outputs the current row of the A
1.2235 + ** select as the next output row of the compound select.
1.2236 + */
1.2237 + VdbeNoopComment((v, "Output routine for A"));
1.2238 + addrOutA = generateOutputSubroutine(pParse,
1.2239 + p, &destA, pDest, regOutA,
1.2240 + regPrev, pKeyDup, P4_KEYINFO_HANDOFF, labelEnd);
1.2241 +
1.2242 + /* Generate a subroutine that outputs the current row of the B
1.2243 + ** select as the next output row of the compound select.
1.2244 + */
1.2245 + if( op==TK_ALL || op==TK_UNION ){
1.2246 + VdbeNoopComment((v, "Output routine for B"));
1.2247 + addrOutB = generateOutputSubroutine(pParse,
1.2248 + p, &destB, pDest, regOutB,
1.2249 + regPrev, pKeyDup, P4_KEYINFO_STATIC, labelEnd);
1.2250 + }
1.2251 +
1.2252 + /* Generate a subroutine to run when the results from select A
1.2253 + ** are exhausted and only data in select B remains.
1.2254 + */
1.2255 + VdbeNoopComment((v, "eof-A subroutine"));
1.2256 + if( op==TK_EXCEPT || op==TK_INTERSECT ){
1.2257 + addrEofA = sqlite3VdbeAddOp2(v, OP_Goto, 0, labelEnd);
1.2258 + }else{
1.2259 + addrEofA = sqlite3VdbeAddOp2(v, OP_If, regEofB, labelEnd);
1.2260 + sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB);
1.2261 + sqlite3VdbeAddOp1(v, OP_Yield, regAddrB);
1.2262 + sqlite3VdbeAddOp2(v, OP_Goto, 0, addrEofA);
1.2263 + }
1.2264 +
1.2265 + /* Generate a subroutine to run when the results from select B
1.2266 + ** are exhausted and only data in select A remains.
1.2267 + */
1.2268 + if( op==TK_INTERSECT ){
1.2269 + addrEofB = addrEofA;
1.2270 + }else{
1.2271 + VdbeNoopComment((v, "eof-B subroutine"));
1.2272 + addrEofB = sqlite3VdbeAddOp2(v, OP_If, regEofA, labelEnd);
1.2273 + sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA);
1.2274 + sqlite3VdbeAddOp1(v, OP_Yield, regAddrA);
1.2275 + sqlite3VdbeAddOp2(v, OP_Goto, 0, addrEofB);
1.2276 + }
1.2277 +
1.2278 + /* Generate code to handle the case of A<B
1.2279 + */
1.2280 + VdbeNoopComment((v, "A-lt-B subroutine"));
1.2281 + addrAltB = sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA);
1.2282 + sqlite3VdbeAddOp1(v, OP_Yield, regAddrA);
1.2283 + sqlite3VdbeAddOp2(v, OP_If, regEofA, addrEofA);
1.2284 + sqlite3VdbeAddOp2(v, OP_Goto, 0, labelCmpr);
1.2285 +
1.2286 + /* Generate code to handle the case of A==B
1.2287 + */
1.2288 + if( op==TK_ALL ){
1.2289 + addrAeqB = addrAltB;
1.2290 + }else if( op==TK_INTERSECT ){
1.2291 + addrAeqB = addrAltB;
1.2292 + addrAltB++;
1.2293 + }else{
1.2294 + VdbeNoopComment((v, "A-eq-B subroutine"));
1.2295 + addrAeqB =
1.2296 + sqlite3VdbeAddOp1(v, OP_Yield, regAddrA);
1.2297 + sqlite3VdbeAddOp2(v, OP_If, regEofA, addrEofA);
1.2298 + sqlite3VdbeAddOp2(v, OP_Goto, 0, labelCmpr);
1.2299 + }
1.2300 +
1.2301 + /* Generate code to handle the case of A>B
1.2302 + */
1.2303 + VdbeNoopComment((v, "A-gt-B subroutine"));
1.2304 + addrAgtB = sqlite3VdbeCurrentAddr(v);
1.2305 + if( op==TK_ALL || op==TK_UNION ){
1.2306 + sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB);
1.2307 + }
1.2308 + sqlite3VdbeAddOp1(v, OP_Yield, regAddrB);
1.2309 + sqlite3VdbeAddOp2(v, OP_If, regEofB, addrEofB);
1.2310 + sqlite3VdbeAddOp2(v, OP_Goto, 0, labelCmpr);
1.2311 +
1.2312 + /* This code runs once to initialize everything.
1.2313 + */
1.2314 + sqlite3VdbeJumpHere(v, j1);
1.2315 + sqlite3VdbeAddOp2(v, OP_Integer, 0, regEofA);
1.2316 + sqlite3VdbeAddOp2(v, OP_Integer, 0, regEofB);
1.2317 + sqlite3VdbeAddOp2(v, OP_Gosub, regAddrA, addrSelectA);
1.2318 + sqlite3VdbeAddOp2(v, OP_Gosub, regAddrB, addrSelectB);
1.2319 + sqlite3VdbeAddOp2(v, OP_If, regEofA, addrEofA);
1.2320 + sqlite3VdbeAddOp2(v, OP_If, regEofB, addrEofB);
1.2321 +
1.2322 + /* Implement the main merge loop
1.2323 + */
1.2324 + sqlite3VdbeResolveLabel(v, labelCmpr);
1.2325 + sqlite3VdbeAddOp4(v, OP_Permutation, 0, 0, 0, (char*)aPermute, P4_INTARRAY);
1.2326 + sqlite3VdbeAddOp4(v, OP_Compare, destA.iMem, destB.iMem, nOrderBy,
1.2327 + (char*)pKeyMerge, P4_KEYINFO_HANDOFF);
1.2328 + sqlite3VdbeAddOp3(v, OP_Jump, addrAltB, addrAeqB, addrAgtB);
1.2329 +
1.2330 + /* Release temporary registers
1.2331 + */
1.2332 + if( regPrev ){
1.2333 + sqlite3ReleaseTempRange(pParse, regPrev, nOrderBy+1);
1.2334 + }
1.2335 +
1.2336 + /* Jump to the this point in order to terminate the query.
1.2337 + */
1.2338 + sqlite3VdbeResolveLabel(v, labelEnd);
1.2339 +
1.2340 + /* Set the number of output columns
1.2341 + */
1.2342 + if( pDest->eDest==SRT_Output ){
1.2343 + Select *pFirst = pPrior;
1.2344 + while( pFirst->pPrior ) pFirst = pFirst->pPrior;
1.2345 + generateColumnNames(pParse, 0, pFirst->pEList);
1.2346 + }
1.2347 +
1.2348 + /* Reassembly the compound query so that it will be freed correctly
1.2349 + ** by the calling function */
1.2350 + if( p->pPrior ){
1.2351 + sqlite3SelectDelete(db, p->pPrior);
1.2352 + }
1.2353 + p->pPrior = pPrior;
1.2354 +
1.2355 + /*** TBD: Insert subroutine calls to close cursors on incomplete
1.2356 + **** subqueries ****/
1.2357 + return SQLITE_OK;
1.2358 +}
1.2359 +#endif
1.2360 +
1.2361 +#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
1.2362 +/* Forward Declarations */
1.2363 +static void substExprList(sqlite3*, ExprList*, int, ExprList*);
1.2364 +static void substSelect(sqlite3*, Select *, int, ExprList *);
1.2365 +
1.2366 +/*
1.2367 +** Scan through the expression pExpr. Replace every reference to
1.2368 +** a column in table number iTable with a copy of the iColumn-th
1.2369 +** entry in pEList. (But leave references to the ROWID column
1.2370 +** unchanged.)
1.2371 +**
1.2372 +** This routine is part of the flattening procedure. A subquery
1.2373 +** whose result set is defined by pEList appears as entry in the
1.2374 +** FROM clause of a SELECT such that the VDBE cursor assigned to that
1.2375 +** FORM clause entry is iTable. This routine make the necessary
1.2376 +** changes to pExpr so that it refers directly to the source table
1.2377 +** of the subquery rather the result set of the subquery.
1.2378 +*/
1.2379 +static void substExpr(
1.2380 + sqlite3 *db, /* Report malloc errors to this connection */
1.2381 + Expr *pExpr, /* Expr in which substitution occurs */
1.2382 + int iTable, /* Table to be substituted */
1.2383 + ExprList *pEList /* Substitute expressions */
1.2384 +){
1.2385 + if( pExpr==0 ) return;
1.2386 + if( pExpr->op==TK_COLUMN && pExpr->iTable==iTable ){
1.2387 + if( pExpr->iColumn<0 ){
1.2388 + pExpr->op = TK_NULL;
1.2389 + }else{
1.2390 + Expr *pNew;
1.2391 + assert( pEList!=0 && pExpr->iColumn<pEList->nExpr );
1.2392 + assert( pExpr->pLeft==0 && pExpr->pRight==0 && pExpr->pList==0 );
1.2393 + pNew = pEList->a[pExpr->iColumn].pExpr;
1.2394 + assert( pNew!=0 );
1.2395 + pExpr->op = pNew->op;
1.2396 + assert( pExpr->pLeft==0 );
1.2397 + pExpr->pLeft = sqlite3ExprDup(db, pNew->pLeft);
1.2398 + assert( pExpr->pRight==0 );
1.2399 + pExpr->pRight = sqlite3ExprDup(db, pNew->pRight);
1.2400 + assert( pExpr->pList==0 );
1.2401 + pExpr->pList = sqlite3ExprListDup(db, pNew->pList);
1.2402 + pExpr->iTable = pNew->iTable;
1.2403 + pExpr->pTab = pNew->pTab;
1.2404 + pExpr->iColumn = pNew->iColumn;
1.2405 + pExpr->iAgg = pNew->iAgg;
1.2406 + sqlite3TokenCopy(db, &pExpr->token, &pNew->token);
1.2407 + sqlite3TokenCopy(db, &pExpr->span, &pNew->span);
1.2408 + pExpr->pSelect = sqlite3SelectDup(db, pNew->pSelect);
1.2409 + pExpr->flags = pNew->flags;
1.2410 + }
1.2411 + }else{
1.2412 + substExpr(db, pExpr->pLeft, iTable, pEList);
1.2413 + substExpr(db, pExpr->pRight, iTable, pEList);
1.2414 + substSelect(db, pExpr->pSelect, iTable, pEList);
1.2415 + substExprList(db, pExpr->pList, iTable, pEList);
1.2416 + }
1.2417 +}
1.2418 +static void substExprList(
1.2419 + sqlite3 *db, /* Report malloc errors here */
1.2420 + ExprList *pList, /* List to scan and in which to make substitutes */
1.2421 + int iTable, /* Table to be substituted */
1.2422 + ExprList *pEList /* Substitute values */
1.2423 +){
1.2424 + int i;
1.2425 + if( pList==0 ) return;
1.2426 + for(i=0; i<pList->nExpr; i++){
1.2427 + substExpr(db, pList->a[i].pExpr, iTable, pEList);
1.2428 + }
1.2429 +}
1.2430 +static void substSelect(
1.2431 + sqlite3 *db, /* Report malloc errors here */
1.2432 + Select *p, /* SELECT statement in which to make substitutions */
1.2433 + int iTable, /* Table to be replaced */
1.2434 + ExprList *pEList /* Substitute values */
1.2435 +){
1.2436 + SrcList *pSrc;
1.2437 + struct SrcList_item *pItem;
1.2438 + int i;
1.2439 + if( !p ) return;
1.2440 + substExprList(db, p->pEList, iTable, pEList);
1.2441 + substExprList(db, p->pGroupBy, iTable, pEList);
1.2442 + substExprList(db, p->pOrderBy, iTable, pEList);
1.2443 + substExpr(db, p->pHaving, iTable, pEList);
1.2444 + substExpr(db, p->pWhere, iTable, pEList);
1.2445 + substSelect(db, p->pPrior, iTable, pEList);
1.2446 + pSrc = p->pSrc;
1.2447 + if( pSrc ){
1.2448 + for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){
1.2449 + substSelect(db, pItem->pSelect, iTable, pEList);
1.2450 + }
1.2451 + }
1.2452 +}
1.2453 +#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */
1.2454 +
1.2455 +#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
1.2456 +/*
1.2457 +** This routine attempts to flatten subqueries in order to speed
1.2458 +** execution. It returns 1 if it makes changes and 0 if no flattening
1.2459 +** occurs.
1.2460 +**
1.2461 +** To understand the concept of flattening, consider the following
1.2462 +** query:
1.2463 +**
1.2464 +** SELECT a FROM (SELECT x+y AS a FROM t1 WHERE z<100) WHERE a>5
1.2465 +**
1.2466 +** The default way of implementing this query is to execute the
1.2467 +** subquery first and store the results in a temporary table, then
1.2468 +** run the outer query on that temporary table. This requires two
1.2469 +** passes over the data. Furthermore, because the temporary table
1.2470 +** has no indices, the WHERE clause on the outer query cannot be
1.2471 +** optimized.
1.2472 +**
1.2473 +** This routine attempts to rewrite queries such as the above into
1.2474 +** a single flat select, like this:
1.2475 +**
1.2476 +** SELECT x+y AS a FROM t1 WHERE z<100 AND a>5
1.2477 +**
1.2478 +** The code generated for this simpification gives the same result
1.2479 +** but only has to scan the data once. And because indices might
1.2480 +** exist on the table t1, a complete scan of the data might be
1.2481 +** avoided.
1.2482 +**
1.2483 +** Flattening is only attempted if all of the following are true:
1.2484 +**
1.2485 +** (1) The subquery and the outer query do not both use aggregates.
1.2486 +**
1.2487 +** (2) The subquery is not an aggregate or the outer query is not a join.
1.2488 +**
1.2489 +** (3) The subquery is not the right operand of a left outer join
1.2490 +** (Originally ticket #306. Strenghtened by ticket #3300)
1.2491 +**
1.2492 +** (4) The subquery is not DISTINCT or the outer query is not a join.
1.2493 +**
1.2494 +** (5) The subquery is not DISTINCT or the outer query does not use
1.2495 +** aggregates.
1.2496 +**
1.2497 +** (6) The subquery does not use aggregates or the outer query is not
1.2498 +** DISTINCT.
1.2499 +**
1.2500 +** (7) The subquery has a FROM clause.
1.2501 +**
1.2502 +** (8) The subquery does not use LIMIT or the outer query is not a join.
1.2503 +**
1.2504 +** (9) The subquery does not use LIMIT or the outer query does not use
1.2505 +** aggregates.
1.2506 +**
1.2507 +** (10) The subquery does not use aggregates or the outer query does not
1.2508 +** use LIMIT.
1.2509 +**
1.2510 +** (11) The subquery and the outer query do not both have ORDER BY clauses.
1.2511 +**
1.2512 +** (12) Not implemented. Subsumed into restriction (3). Was previously
1.2513 +** a separate restriction deriving from ticket #350.
1.2514 +**
1.2515 +** (13) The subquery and outer query do not both use LIMIT
1.2516 +**
1.2517 +** (14) The subquery does not use OFFSET
1.2518 +**
1.2519 +** (15) The outer query is not part of a compound select or the
1.2520 +** subquery does not have both an ORDER BY and a LIMIT clause.
1.2521 +** (See ticket #2339)
1.2522 +**
1.2523 +** (16) The outer query is not an aggregate or the subquery does
1.2524 +** not contain ORDER BY. (Ticket #2942) This used to not matter
1.2525 +** until we introduced the group_concat() function.
1.2526 +**
1.2527 +** (17) The sub-query is not a compound select, or it is a UNION ALL
1.2528 +** compound clause made up entirely of non-aggregate queries, and
1.2529 +** the parent query:
1.2530 +**
1.2531 +** * is not itself part of a compound select,
1.2532 +** * is not an aggregate or DISTINCT query, and
1.2533 +** * has no other tables or sub-selects in the FROM clause.
1.2534 +**
1.2535 +** The parent and sub-query may contain WHERE clauses. Subject to
1.2536 +** rules (11), (13) and (14), they may also contain ORDER BY,
1.2537 +** LIMIT and OFFSET clauses.
1.2538 +**
1.2539 +** (18) If the sub-query is a compound select, then all terms of the
1.2540 +** ORDER by clause of the parent must be simple references to
1.2541 +** columns of the sub-query.
1.2542 +**
1.2543 +** (19) The subquery does not use LIMIT or the outer query does not
1.2544 +** have a WHERE clause.
1.2545 +**
1.2546 +** In this routine, the "p" parameter is a pointer to the outer query.
1.2547 +** The subquery is p->pSrc->a[iFrom]. isAgg is true if the outer query
1.2548 +** uses aggregates and subqueryIsAgg is true if the subquery uses aggregates.
1.2549 +**
1.2550 +** If flattening is not attempted, this routine is a no-op and returns 0.
1.2551 +** If flattening is attempted this routine returns 1.
1.2552 +**
1.2553 +** All of the expression analysis must occur on both the outer query and
1.2554 +** the subquery before this routine runs.
1.2555 +*/
1.2556 +static int flattenSubquery(
1.2557 + Parse *pParse, /* Parsing context */
1.2558 + Select *p, /* The parent or outer SELECT statement */
1.2559 + int iFrom, /* Index in p->pSrc->a[] of the inner subquery */
1.2560 + int isAgg, /* True if outer SELECT uses aggregate functions */
1.2561 + int subqueryIsAgg /* True if the subquery uses aggregate functions */
1.2562 +){
1.2563 + const char *zSavedAuthContext = pParse->zAuthContext;
1.2564 + Select *pParent;
1.2565 + Select *pSub; /* The inner query or "subquery" */
1.2566 + Select *pSub1; /* Pointer to the rightmost select in sub-query */
1.2567 + SrcList *pSrc; /* The FROM clause of the outer query */
1.2568 + SrcList *pSubSrc; /* The FROM clause of the subquery */
1.2569 + ExprList *pList; /* The result set of the outer query */
1.2570 + int iParent; /* VDBE cursor number of the pSub result set temp table */
1.2571 + int i; /* Loop counter */
1.2572 + Expr *pWhere; /* The WHERE clause */
1.2573 + struct SrcList_item *pSubitem; /* The subquery */
1.2574 + sqlite3 *db = pParse->db;
1.2575 +
1.2576 + /* Check to see if flattening is permitted. Return 0 if not.
1.2577 + */
1.2578 + if( p==0 ) return 0;
1.2579 + pSrc = p->pSrc;
1.2580 + assert( pSrc && iFrom>=0 && iFrom<pSrc->nSrc );
1.2581 + pSubitem = &pSrc->a[iFrom];
1.2582 + iParent = pSubitem->iCursor;
1.2583 + pSub = pSubitem->pSelect;
1.2584 + assert( pSub!=0 );
1.2585 + if( isAgg && subqueryIsAgg ) return 0; /* Restriction (1) */
1.2586 + if( subqueryIsAgg && pSrc->nSrc>1 ) return 0; /* Restriction (2) */
1.2587 + pSubSrc = pSub->pSrc;
1.2588 + assert( pSubSrc );
1.2589 + /* Prior to version 3.1.2, when LIMIT and OFFSET had to be simple constants,
1.2590 + ** not arbitrary expresssions, we allowed some combining of LIMIT and OFFSET
1.2591 + ** because they could be computed at compile-time. But when LIMIT and OFFSET
1.2592 + ** became arbitrary expressions, we were forced to add restrictions (13)
1.2593 + ** and (14). */
1.2594 + if( pSub->pLimit && p->pLimit ) return 0; /* Restriction (13) */
1.2595 + if( pSub->pOffset ) return 0; /* Restriction (14) */
1.2596 + if( p->pRightmost && pSub->pLimit && pSub->pOrderBy ){
1.2597 + return 0; /* Restriction (15) */
1.2598 + }
1.2599 + if( pSubSrc->nSrc==0 ) return 0; /* Restriction (7) */
1.2600 + if( ((pSub->selFlags & SF_Distinct)!=0 || pSub->pLimit)
1.2601 + && (pSrc->nSrc>1 || isAgg) ){ /* Restrictions (4)(5)(8)(9) */
1.2602 + return 0;
1.2603 + }
1.2604 + if( (p->selFlags & SF_Distinct)!=0 && subqueryIsAgg ){
1.2605 + return 0; /* Restriction (6) */
1.2606 + }
1.2607 + if( p->pOrderBy && pSub->pOrderBy ){
1.2608 + return 0; /* Restriction (11) */
1.2609 + }
1.2610 + if( isAgg && pSub->pOrderBy ) return 0; /* Restriction (16) */
1.2611 + if( pSub->pLimit && p->pWhere ) return 0; /* Restriction (19) */
1.2612 +
1.2613 + /* OBSOLETE COMMENT 1:
1.2614 + ** Restriction 3: If the subquery is a join, make sure the subquery is
1.2615 + ** not used as the right operand of an outer join. Examples of why this
1.2616 + ** is not allowed:
1.2617 + **
1.2618 + ** t1 LEFT OUTER JOIN (t2 JOIN t3)
1.2619 + **
1.2620 + ** If we flatten the above, we would get
1.2621 + **
1.2622 + ** (t1 LEFT OUTER JOIN t2) JOIN t3
1.2623 + **
1.2624 + ** which is not at all the same thing.
1.2625 + **
1.2626 + ** OBSOLETE COMMENT 2:
1.2627 + ** Restriction 12: If the subquery is the right operand of a left outer
1.2628 + ** join, make sure the subquery has no WHERE clause.
1.2629 + ** An examples of why this is not allowed:
1.2630 + **
1.2631 + ** t1 LEFT OUTER JOIN (SELECT * FROM t2 WHERE t2.x>0)
1.2632 + **
1.2633 + ** If we flatten the above, we would get
1.2634 + **
1.2635 + ** (t1 LEFT OUTER JOIN t2) WHERE t2.x>0
1.2636 + **
1.2637 + ** But the t2.x>0 test will always fail on a NULL row of t2, which
1.2638 + ** effectively converts the OUTER JOIN into an INNER JOIN.
1.2639 + **
1.2640 + ** THIS OVERRIDES OBSOLETE COMMENTS 1 AND 2 ABOVE:
1.2641 + ** Ticket #3300 shows that flattening the right term of a LEFT JOIN
1.2642 + ** is fraught with danger. Best to avoid the whole thing. If the
1.2643 + ** subquery is the right term of a LEFT JOIN, then do not flatten.
1.2644 + */
1.2645 + if( (pSubitem->jointype & JT_OUTER)!=0 ){
1.2646 + return 0;
1.2647 + }
1.2648 +
1.2649 + /* Restriction 17: If the sub-query is a compound SELECT, then it must
1.2650 + ** use only the UNION ALL operator. And none of the simple select queries
1.2651 + ** that make up the compound SELECT are allowed to be aggregate or distinct
1.2652 + ** queries.
1.2653 + */
1.2654 + if( pSub->pPrior ){
1.2655 + if( p->pPrior || isAgg || (p->selFlags & SF_Distinct)!=0 || pSrc->nSrc!=1 ){
1.2656 + return 0;
1.2657 + }
1.2658 + for(pSub1=pSub; pSub1; pSub1=pSub1->pPrior){
1.2659 + if( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))!=0
1.2660 + || (pSub1->pPrior && pSub1->op!=TK_ALL)
1.2661 + || !pSub1->pSrc || pSub1->pSrc->nSrc!=1
1.2662 + ){
1.2663 + return 0;
1.2664 + }
1.2665 + }
1.2666 +
1.2667 + /* Restriction 18. */
1.2668 + if( p->pOrderBy ){
1.2669 + int ii;
1.2670 + for(ii=0; ii<p->pOrderBy->nExpr; ii++){
1.2671 + if( p->pOrderBy->a[ii].iCol==0 ) return 0;
1.2672 + }
1.2673 + }
1.2674 + }
1.2675 +
1.2676 + /***** If we reach this point, flattening is permitted. *****/
1.2677 +
1.2678 + /* Authorize the subquery */
1.2679 + pParse->zAuthContext = pSubitem->zName;
1.2680 + sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0);
1.2681 + pParse->zAuthContext = zSavedAuthContext;
1.2682 +
1.2683 + /* If the sub-query is a compound SELECT statement, then (by restrictions
1.2684 + ** 17 and 18 above) it must be a UNION ALL and the parent query must
1.2685 + ** be of the form:
1.2686 + **
1.2687 + ** SELECT <expr-list> FROM (<sub-query>) <where-clause>
1.2688 + **
1.2689 + ** followed by any ORDER BY, LIMIT and/or OFFSET clauses. This block
1.2690 + ** creates N copies of the parent query without any ORDER BY, LIMIT or
1.2691 + ** OFFSET clauses and joins them to the left-hand-side of the original
1.2692 + ** using UNION ALL operators. In this case N is the number of simple
1.2693 + ** select statements in the compound sub-query.
1.2694 + */
1.2695 + for(pSub=pSub->pPrior; pSub; pSub=pSub->pPrior){
1.2696 + Select *pNew;
1.2697 + ExprList *pOrderBy = p->pOrderBy;
1.2698 + Expr *pLimit = p->pLimit;
1.2699 + Expr *pOffset = p->pOffset;
1.2700 + Select *pPrior = p->pPrior;
1.2701 + p->pOrderBy = 0;
1.2702 + p->pSrc = 0;
1.2703 + p->pPrior = 0;
1.2704 + p->pLimit = 0;
1.2705 + pNew = sqlite3SelectDup(db, p);
1.2706 + pNew->pPrior = pPrior;
1.2707 + p->pPrior = pNew;
1.2708 + p->pOrderBy = pOrderBy;
1.2709 + p->op = TK_ALL;
1.2710 + p->pSrc = pSrc;
1.2711 + p->pLimit = pLimit;
1.2712 + p->pOffset = pOffset;
1.2713 + p->pRightmost = 0;
1.2714 + pNew->pRightmost = 0;
1.2715 + }
1.2716 +
1.2717 + /* Begin flattening the iFrom-th entry of the FROM clause
1.2718 + ** in the outer query.
1.2719 + */
1.2720 + pSub = pSub1 = pSubitem->pSelect;
1.2721 + for(pParent=p; pParent; pParent=pParent->pPrior, pSub=pSub->pPrior){
1.2722 + int nSubSrc = pSubSrc->nSrc;
1.2723 + int jointype = 0;
1.2724 + pSubSrc = pSub->pSrc;
1.2725 + pSrc = pParent->pSrc;
1.2726 +
1.2727 + /* Move all of the FROM elements of the subquery into the
1.2728 + ** the FROM clause of the outer query. Before doing this, remember
1.2729 + ** the cursor number for the original outer query FROM element in
1.2730 + ** iParent. The iParent cursor will never be used. Subsequent code
1.2731 + ** will scan expressions looking for iParent references and replace
1.2732 + ** those references with expressions that resolve to the subquery FROM
1.2733 + ** elements we are now copying in.
1.2734 + */
1.2735 + if( pSrc ){
1.2736 + Table *pTabToDel;
1.2737 + pSubitem = &pSrc->a[iFrom];
1.2738 + nSubSrc = pSubSrc->nSrc;
1.2739 + jointype = pSubitem->jointype;
1.2740 + sqlite3DbFree(db, pSubitem->zDatabase);
1.2741 + sqlite3DbFree(db, pSubitem->zName);
1.2742 + sqlite3DbFree(db, pSubitem->zAlias);
1.2743 + pSubitem->zDatabase = 0;
1.2744 + pSubitem->zName = 0;
1.2745 + pSubitem->zAlias = 0;
1.2746 +
1.2747 + /* If the FROM element is a subquery, defer deleting the Table
1.2748 + ** object associated with that subquery until code generation is
1.2749 + ** complete, since there may still exist Expr.pTab entires that
1.2750 + ** refer to the subquery even after flattening. Ticket #3346.
1.2751 + */
1.2752 + if( (pTabToDel = pSubitem->pTab)!=0 ){
1.2753 + if( pTabToDel->nRef==1 ){
1.2754 + pTabToDel->pNextZombie = pParse->pZombieTab;
1.2755 + pParse->pZombieTab = pTabToDel;
1.2756 + }else{
1.2757 + pTabToDel->nRef--;
1.2758 + }
1.2759 + }
1.2760 + pSubitem->pTab = 0;
1.2761 + }
1.2762 + if( nSubSrc!=1 || !pSrc ){
1.2763 + int extra = nSubSrc - 1;
1.2764 + for(i=(pSrc?1:0); i<nSubSrc; i++){
1.2765 + pSrc = sqlite3SrcListAppend(db, pSrc, 0, 0);
1.2766 + if( pSrc==0 ){
1.2767 + pParent->pSrc = 0;
1.2768 + return 1;
1.2769 + }
1.2770 + }
1.2771 + pParent->pSrc = pSrc;
1.2772 + for(i=pSrc->nSrc-1; i-extra>=iFrom; i--){
1.2773 + pSrc->a[i] = pSrc->a[i-extra];
1.2774 + }
1.2775 + }
1.2776 + for(i=0; i<nSubSrc; i++){
1.2777 + pSrc->a[i+iFrom] = pSubSrc->a[i];
1.2778 + memset(&pSubSrc->a[i], 0, sizeof(pSubSrc->a[i]));
1.2779 + }
1.2780 + pSrc->a[iFrom].jointype = jointype;
1.2781 +
1.2782 + /* Now begin substituting subquery result set expressions for
1.2783 + ** references to the iParent in the outer query.
1.2784 + **
1.2785 + ** Example:
1.2786 + **
1.2787 + ** SELECT a+5, b*10 FROM (SELECT x*3 AS a, y+10 AS b FROM t1) WHERE a>b;
1.2788 + ** \ \_____________ subquery __________/ /
1.2789 + ** \_____________________ outer query ______________________________/
1.2790 + **
1.2791 + ** We look at every expression in the outer query and every place we see
1.2792 + ** "a" we substitute "x*3" and every place we see "b" we substitute "y+10".
1.2793 + */
1.2794 + pList = pParent->pEList;
1.2795 + for(i=0; i<pList->nExpr; i++){
1.2796 + Expr *pExpr;
1.2797 + if( pList->a[i].zName==0 && (pExpr = pList->a[i].pExpr)->span.z!=0 ){
1.2798 + pList->a[i].zName =
1.2799 + sqlite3DbStrNDup(db, (char*)pExpr->span.z, pExpr->span.n);
1.2800 + }
1.2801 + }
1.2802 + substExprList(db, pParent->pEList, iParent, pSub->pEList);
1.2803 + if( isAgg ){
1.2804 + substExprList(db, pParent->pGroupBy, iParent, pSub->pEList);
1.2805 + substExpr(db, pParent->pHaving, iParent, pSub->pEList);
1.2806 + }
1.2807 + if( pSub->pOrderBy ){
1.2808 + assert( pParent->pOrderBy==0 );
1.2809 + pParent->pOrderBy = pSub->pOrderBy;
1.2810 + pSub->pOrderBy = 0;
1.2811 + }else if( pParent->pOrderBy ){
1.2812 + substExprList(db, pParent->pOrderBy, iParent, pSub->pEList);
1.2813 + }
1.2814 + if( pSub->pWhere ){
1.2815 + pWhere = sqlite3ExprDup(db, pSub->pWhere);
1.2816 + }else{
1.2817 + pWhere = 0;
1.2818 + }
1.2819 + if( subqueryIsAgg ){
1.2820 + assert( pParent->pHaving==0 );
1.2821 + pParent->pHaving = pParent->pWhere;
1.2822 + pParent->pWhere = pWhere;
1.2823 + substExpr(db, pParent->pHaving, iParent, pSub->pEList);
1.2824 + pParent->pHaving = sqlite3ExprAnd(db, pParent->pHaving,
1.2825 + sqlite3ExprDup(db, pSub->pHaving));
1.2826 + assert( pParent->pGroupBy==0 );
1.2827 + pParent->pGroupBy = sqlite3ExprListDup(db, pSub->pGroupBy);
1.2828 + }else{
1.2829 + substExpr(db, pParent->pWhere, iParent, pSub->pEList);
1.2830 + pParent->pWhere = sqlite3ExprAnd(db, pParent->pWhere, pWhere);
1.2831 + }
1.2832 +
1.2833 + /* The flattened query is distinct if either the inner or the
1.2834 + ** outer query is distinct.
1.2835 + */
1.2836 + pParent->selFlags |= pSub->selFlags & SF_Distinct;
1.2837 +
1.2838 + /*
1.2839 + ** SELECT ... FROM (SELECT ... LIMIT a OFFSET b) LIMIT x OFFSET y;
1.2840 + **
1.2841 + ** One is tempted to try to add a and b to combine the limits. But this
1.2842 + ** does not work if either limit is negative.
1.2843 + */
1.2844 + if( pSub->pLimit ){
1.2845 + pParent->pLimit = pSub->pLimit;
1.2846 + pSub->pLimit = 0;
1.2847 + }
1.2848 + }
1.2849 +
1.2850 + /* Finially, delete what is left of the subquery and return
1.2851 + ** success.
1.2852 + */
1.2853 + sqlite3SelectDelete(db, pSub1);
1.2854 +
1.2855 + return 1;
1.2856 +}
1.2857 +#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */
1.2858 +
1.2859 +/*
1.2860 +** Analyze the SELECT statement passed as an argument to see if it
1.2861 +** is a min() or max() query. Return WHERE_ORDERBY_MIN or WHERE_ORDERBY_MAX if
1.2862 +** it is, or 0 otherwise. At present, a query is considered to be
1.2863 +** a min()/max() query if:
1.2864 +**
1.2865 +** 1. There is a single object in the FROM clause.
1.2866 +**
1.2867 +** 2. There is a single expression in the result set, and it is
1.2868 +** either min(x) or max(x), where x is a column reference.
1.2869 +*/
1.2870 +static int minMaxQuery(Parse *pParse, Select *p){
1.2871 + Expr *pExpr;
1.2872 + ExprList *pEList = p->pEList;
1.2873 +
1.2874 + if( pEList->nExpr!=1 ) return WHERE_ORDERBY_NORMAL;
1.2875 + pExpr = pEList->a[0].pExpr;
1.2876 + pEList = pExpr->pList;
1.2877 + if( pExpr->op!=TK_AGG_FUNCTION || pEList==0 || pEList->nExpr!=1 ) return 0;
1.2878 + if( pEList->a[0].pExpr->op!=TK_AGG_COLUMN ) return WHERE_ORDERBY_NORMAL;
1.2879 + if( pExpr->token.n!=3 ) return WHERE_ORDERBY_NORMAL;
1.2880 + if( sqlite3StrNICmp((char*)pExpr->token.z,"min",3)==0 ){
1.2881 + return WHERE_ORDERBY_MIN;
1.2882 + }else if( sqlite3StrNICmp((char*)pExpr->token.z,"max",3)==0 ){
1.2883 + return WHERE_ORDERBY_MAX;
1.2884 + }
1.2885 + return WHERE_ORDERBY_NORMAL;
1.2886 +}
1.2887 +
1.2888 +/*
1.2889 +** This routine is a Walker callback for "expanding" a SELECT statement.
1.2890 +** "Expanding" means to do the following:
1.2891 +**
1.2892 +** (1) Make sure VDBE cursor numbers have been assigned to every
1.2893 +** element of the FROM clause.
1.2894 +**
1.2895 +** (2) Fill in the pTabList->a[].pTab fields in the SrcList that
1.2896 +** defines FROM clause. When views appear in the FROM clause,
1.2897 +** fill pTabList->a[].pSelect with a copy of the SELECT statement
1.2898 +** that implements the view. A copy is made of the view's SELECT
1.2899 +** statement so that we can freely modify or delete that statement
1.2900 +** without worrying about messing up the presistent representation
1.2901 +** of the view.
1.2902 +**
1.2903 +** (3) Add terms to the WHERE clause to accomodate the NATURAL keyword
1.2904 +** on joins and the ON and USING clause of joins.
1.2905 +**
1.2906 +** (4) Scan the list of columns in the result set (pEList) looking
1.2907 +** for instances of the "*" operator or the TABLE.* operator.
1.2908 +** If found, expand each "*" to be every column in every table
1.2909 +** and TABLE.* to be every column in TABLE.
1.2910 +**
1.2911 +*/
1.2912 +static int selectExpander(Walker *pWalker, Select *p){
1.2913 + Parse *pParse = pWalker->pParse;
1.2914 + int i, j, k;
1.2915 + SrcList *pTabList;
1.2916 + ExprList *pEList;
1.2917 + struct SrcList_item *pFrom;
1.2918 + sqlite3 *db = pParse->db;
1.2919 +
1.2920 + if( db->mallocFailed ){
1.2921 + return WRC_Abort;
1.2922 + }
1.2923 + if( p->pSrc==0 || (p->selFlags & SF_Expanded)!=0 ){
1.2924 + return WRC_Prune;
1.2925 + }
1.2926 + p->selFlags |= SF_Expanded;
1.2927 + pTabList = p->pSrc;
1.2928 + pEList = p->pEList;
1.2929 +
1.2930 + /* Make sure cursor numbers have been assigned to all entries in
1.2931 + ** the FROM clause of the SELECT statement.
1.2932 + */
1.2933 + sqlite3SrcListAssignCursors(pParse, pTabList);
1.2934 +
1.2935 + /* Look up every table named in the FROM clause of the select. If
1.2936 + ** an entry of the FROM clause is a subquery instead of a table or view,
1.2937 + ** then create a transient table structure to describe the subquery.
1.2938 + */
1.2939 + for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
1.2940 + Table *pTab;
1.2941 + if( pFrom->pTab!=0 ){
1.2942 + /* This statement has already been prepared. There is no need
1.2943 + ** to go further. */
1.2944 + assert( i==0 );
1.2945 + return WRC_Prune;
1.2946 + }
1.2947 + if( pFrom->zName==0 ){
1.2948 +#ifndef SQLITE_OMIT_SUBQUERY
1.2949 + Select *pSel = pFrom->pSelect;
1.2950 + /* A sub-query in the FROM clause of a SELECT */
1.2951 + assert( pSel!=0 );
1.2952 + assert( pFrom->pTab==0 );
1.2953 + sqlite3WalkSelect(pWalker, pSel);
1.2954 + pFrom->pTab = pTab = sqlite3DbMallocZero(db, sizeof(Table));
1.2955 + if( pTab==0 ) return WRC_Abort;
1.2956 + pTab->db = db;
1.2957 + pTab->nRef = 1;
1.2958 + pTab->zName = sqlite3MPrintf(db, "sqlite_subquery_%p_", (void*)pTab);
1.2959 + while( pSel->pPrior ){ pSel = pSel->pPrior; }
1.2960 + selectColumnsFromExprList(pParse, pSel->pEList, &pTab->nCol, &pTab->aCol);
1.2961 + pTab->iPKey = -1;
1.2962 + pTab->tabFlags |= TF_Ephemeral;
1.2963 +#endif
1.2964 + }else{
1.2965 + /* An ordinary table or view name in the FROM clause */
1.2966 + assert( pFrom->pTab==0 );
1.2967 + pFrom->pTab = pTab =
1.2968 + sqlite3LocateTable(pParse,0,pFrom->zName,pFrom->zDatabase);
1.2969 + if( pTab==0 ) return WRC_Abort;
1.2970 + pTab->nRef++;
1.2971 +#if !defined(SQLITE_OMIT_VIEW) || !defined (SQLITE_OMIT_VIRTUALTABLE)
1.2972 + if( pTab->pSelect || IsVirtual(pTab) ){
1.2973 + /* We reach here if the named table is a really a view */
1.2974 + if( sqlite3ViewGetColumnNames(pParse, pTab) ) return WRC_Abort;
1.2975 +
1.2976 + /* If pFrom->pSelect!=0 it means we are dealing with a
1.2977 + ** view within a view. The SELECT structure has already been
1.2978 + ** copied by the outer view so we can skip the copy step here
1.2979 + ** in the inner view.
1.2980 + */
1.2981 + if( pFrom->pSelect==0 ){
1.2982 + pFrom->pSelect = sqlite3SelectDup(db, pTab->pSelect);
1.2983 + sqlite3WalkSelect(pWalker, pFrom->pSelect);
1.2984 + }
1.2985 + }
1.2986 +#endif
1.2987 + }
1.2988 + }
1.2989 +
1.2990 + /* Process NATURAL keywords, and ON and USING clauses of joins.
1.2991 + */
1.2992 + if( db->mallocFailed || sqliteProcessJoin(pParse, p) ){
1.2993 + return WRC_Abort;
1.2994 + }
1.2995 +
1.2996 + /* For every "*" that occurs in the column list, insert the names of
1.2997 + ** all columns in all tables. And for every TABLE.* insert the names
1.2998 + ** of all columns in TABLE. The parser inserted a special expression
1.2999 + ** with the TK_ALL operator for each "*" that it found in the column list.
1.3000 + ** The following code just has to locate the TK_ALL expressions and expand
1.3001 + ** each one to the list of all columns in all tables.
1.3002 + **
1.3003 + ** The first loop just checks to see if there are any "*" operators
1.3004 + ** that need expanding.
1.3005 + */
1.3006 + for(k=0; k<pEList->nExpr; k++){
1.3007 + Expr *pE = pEList->a[k].pExpr;
1.3008 + if( pE->op==TK_ALL ) break;
1.3009 + if( pE->op==TK_DOT && pE->pRight && pE->pRight->op==TK_ALL
1.3010 + && pE->pLeft && pE->pLeft->op==TK_ID ) break;
1.3011 + }
1.3012 + if( k<pEList->nExpr ){
1.3013 + /*
1.3014 + ** If we get here it means the result set contains one or more "*"
1.3015 + ** operators that need to be expanded. Loop through each expression
1.3016 + ** in the result set and expand them one by one.
1.3017 + */
1.3018 + struct ExprList_item *a = pEList->a;
1.3019 + ExprList *pNew = 0;
1.3020 + int flags = pParse->db->flags;
1.3021 + int longNames = (flags & SQLITE_FullColNames)!=0
1.3022 + && (flags & SQLITE_ShortColNames)==0;
1.3023 +
1.3024 + for(k=0; k<pEList->nExpr; k++){
1.3025 + Expr *pE = a[k].pExpr;
1.3026 + if( pE->op!=TK_ALL &&
1.3027 + (pE->op!=TK_DOT || pE->pRight==0 || pE->pRight->op!=TK_ALL) ){
1.3028 + /* This particular expression does not need to be expanded.
1.3029 + */
1.3030 + pNew = sqlite3ExprListAppend(pParse, pNew, a[k].pExpr, 0);
1.3031 + if( pNew ){
1.3032 + pNew->a[pNew->nExpr-1].zName = a[k].zName;
1.3033 + }
1.3034 + a[k].pExpr = 0;
1.3035 + a[k].zName = 0;
1.3036 + }else{
1.3037 + /* This expression is a "*" or a "TABLE.*" and needs to be
1.3038 + ** expanded. */
1.3039 + int tableSeen = 0; /* Set to 1 when TABLE matches */
1.3040 + char *zTName; /* text of name of TABLE */
1.3041 + if( pE->op==TK_DOT && pE->pLeft ){
1.3042 + zTName = sqlite3NameFromToken(db, &pE->pLeft->token);
1.3043 + }else{
1.3044 + zTName = 0;
1.3045 + }
1.3046 + for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
1.3047 + Table *pTab = pFrom->pTab;
1.3048 + char *zTabName = pFrom->zAlias;
1.3049 + if( zTabName==0 || zTabName[0]==0 ){
1.3050 + zTabName = pTab->zName;
1.3051 + }
1.3052 + if( db->mallocFailed ) break;
1.3053 + if( zTName && sqlite3StrICmp(zTName, zTabName)!=0 ){
1.3054 + continue;
1.3055 + }
1.3056 + tableSeen = 1;
1.3057 + for(j=0; j<pTab->nCol; j++){
1.3058 + Expr *pExpr, *pRight;
1.3059 + char *zName = pTab->aCol[j].zName;
1.3060 +
1.3061 + /* If a column is marked as 'hidden' (currently only possible
1.3062 + ** for virtual tables), do not include it in the expanded
1.3063 + ** result-set list.
1.3064 + */
1.3065 + if( IsHiddenColumn(&pTab->aCol[j]) ){
1.3066 + assert(IsVirtual(pTab));
1.3067 + continue;
1.3068 + }
1.3069 +
1.3070 + if( i>0 ){
1.3071 + struct SrcList_item *pLeft = &pTabList->a[i-1];
1.3072 + if( (pLeft[1].jointype & JT_NATURAL)!=0 &&
1.3073 + columnIndex(pLeft->pTab, zName)>=0 ){
1.3074 + /* In a NATURAL join, omit the join columns from the
1.3075 + ** table on the right */
1.3076 + continue;
1.3077 + }
1.3078 + if( sqlite3IdListIndex(pLeft[1].pUsing, zName)>=0 ){
1.3079 + /* In a join with a USING clause, omit columns in the
1.3080 + ** using clause from the table on the right. */
1.3081 + continue;
1.3082 + }
1.3083 + }
1.3084 + pRight = sqlite3PExpr(pParse, TK_ID, 0, 0, 0);
1.3085 + if( pRight==0 ) break;
1.3086 + setQuotedToken(pParse, &pRight->token, zName);
1.3087 + if( longNames || pTabList->nSrc>1 ){
1.3088 + Expr *pLeft = sqlite3PExpr(pParse, TK_ID, 0, 0, 0);
1.3089 + pExpr = sqlite3PExpr(pParse, TK_DOT, pLeft, pRight, 0);
1.3090 + if( pExpr==0 ) break;
1.3091 + setQuotedToken(pParse, &pLeft->token, zTabName);
1.3092 + setToken(&pExpr->span,
1.3093 + sqlite3MPrintf(db, "%s.%s", zTabName, zName));
1.3094 + pExpr->span.dyn = 1;
1.3095 + pExpr->token.z = 0;
1.3096 + pExpr->token.n = 0;
1.3097 + pExpr->token.dyn = 0;
1.3098 + }else{
1.3099 + pExpr = pRight;
1.3100 + pExpr->span = pExpr->token;
1.3101 + pExpr->span.dyn = 0;
1.3102 + }
1.3103 + if( longNames ){
1.3104 + pNew = sqlite3ExprListAppend(pParse, pNew, pExpr, &pExpr->span);
1.3105 + }else{
1.3106 + pNew = sqlite3ExprListAppend(pParse, pNew, pExpr, &pRight->token);
1.3107 + }
1.3108 + }
1.3109 + }
1.3110 + if( !tableSeen ){
1.3111 + if( zTName ){
1.3112 + sqlite3ErrorMsg(pParse, "no such table: %s", zTName);
1.3113 + }else{
1.3114 + sqlite3ErrorMsg(pParse, "no tables specified");
1.3115 + }
1.3116 + }
1.3117 + sqlite3DbFree(db, zTName);
1.3118 + }
1.3119 + }
1.3120 + sqlite3ExprListDelete(db, pEList);
1.3121 + p->pEList = pNew;
1.3122 + }
1.3123 +#if SQLITE_MAX_COLUMN
1.3124 + if( p->pEList && p->pEList->nExpr>db->aLimit[SQLITE_LIMIT_COLUMN] ){
1.3125 + sqlite3ErrorMsg(pParse, "too many columns in result set");
1.3126 + }
1.3127 +#endif
1.3128 + return WRC_Continue;
1.3129 +}
1.3130 +
1.3131 +/*
1.3132 +** No-op routine for the parse-tree walker.
1.3133 +**
1.3134 +** When this routine is the Walker.xExprCallback then expression trees
1.3135 +** are walked without any actions being taken at each node. Presumably,
1.3136 +** when this routine is used for Walker.xExprCallback then
1.3137 +** Walker.xSelectCallback is set to do something useful for every
1.3138 +** subquery in the parser tree.
1.3139 +*/
1.3140 +static int exprWalkNoop(Walker *pWalker, Expr *pExpr){
1.3141 + return WRC_Continue;
1.3142 +}
1.3143 +
1.3144 +/*
1.3145 +** This routine "expands" a SELECT statement and all of its subqueries.
1.3146 +** For additional information on what it means to "expand" a SELECT
1.3147 +** statement, see the comment on the selectExpand worker callback above.
1.3148 +**
1.3149 +** Expanding a SELECT statement is the first step in processing a
1.3150 +** SELECT statement. The SELECT statement must be expanded before
1.3151 +** name resolution is performed.
1.3152 +**
1.3153 +** If anything goes wrong, an error message is written into pParse.
1.3154 +** The calling function can detect the problem by looking at pParse->nErr
1.3155 +** and/or pParse->db->mallocFailed.
1.3156 +*/
1.3157 +static void sqlite3SelectExpand(Parse *pParse, Select *pSelect){
1.3158 + Walker w;
1.3159 + w.xSelectCallback = selectExpander;
1.3160 + w.xExprCallback = exprWalkNoop;
1.3161 + w.pParse = pParse;
1.3162 + sqlite3WalkSelect(&w, pSelect);
1.3163 +}
1.3164 +
1.3165 +
1.3166 +#ifndef SQLITE_OMIT_SUBQUERY
1.3167 +/*
1.3168 +** This is a Walker.xSelectCallback callback for the sqlite3SelectTypeInfo()
1.3169 +** interface.
1.3170 +**
1.3171 +** For each FROM-clause subquery, add Column.zType and Column.zColl
1.3172 +** information to the Table structure that represents the result set
1.3173 +** of that subquery.
1.3174 +**
1.3175 +** The Table structure that represents the result set was constructed
1.3176 +** by selectExpander() but the type and collation information was omitted
1.3177 +** at that point because identifiers had not yet been resolved. This
1.3178 +** routine is called after identifier resolution.
1.3179 +*/
1.3180 +static int selectAddSubqueryTypeInfo(Walker *pWalker, Select *p){
1.3181 + Parse *pParse;
1.3182 + int i;
1.3183 + SrcList *pTabList;
1.3184 + struct SrcList_item *pFrom;
1.3185 +
1.3186 + assert( p->selFlags & SF_Resolved );
1.3187 + if( (p->selFlags & SF_HasTypeInfo)==0 ){
1.3188 + p->selFlags |= SF_HasTypeInfo;
1.3189 + pParse = pWalker->pParse;
1.3190 + pTabList = p->pSrc;
1.3191 + for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
1.3192 + Table *pTab = pFrom->pTab;
1.3193 + if( pTab && (pTab->tabFlags & TF_Ephemeral)!=0 ){
1.3194 + /* A sub-query in the FROM clause of a SELECT */
1.3195 + Select *pSel = pFrom->pSelect;
1.3196 + assert( pSel );
1.3197 + while( pSel->pPrior ) pSel = pSel->pPrior;
1.3198 + selectAddColumnTypeAndCollation(pParse, pTab->nCol, pTab->aCol, pSel);
1.3199 + }
1.3200 + }
1.3201 + }
1.3202 + return WRC_Continue;
1.3203 +}
1.3204 +#endif
1.3205 +
1.3206 +
1.3207 +/*
1.3208 +** This routine adds datatype and collating sequence information to
1.3209 +** the Table structures of all FROM-clause subqueries in a
1.3210 +** SELECT statement.
1.3211 +**
1.3212 +** Use this routine after name resolution.
1.3213 +*/
1.3214 +static void sqlite3SelectAddTypeInfo(Parse *pParse, Select *pSelect){
1.3215 +#ifndef SQLITE_OMIT_SUBQUERY
1.3216 + Walker w;
1.3217 + w.xSelectCallback = selectAddSubqueryTypeInfo;
1.3218 + w.xExprCallback = exprWalkNoop;
1.3219 + w.pParse = pParse;
1.3220 + sqlite3WalkSelect(&w, pSelect);
1.3221 +#endif
1.3222 +}
1.3223 +
1.3224 +
1.3225 +/*
1.3226 +** This routine sets of a SELECT statement for processing. The
1.3227 +** following is accomplished:
1.3228 +**
1.3229 +** * VDBE Cursor numbers are assigned to all FROM-clause terms.
1.3230 +** * Ephemeral Table objects are created for all FROM-clause subqueries.
1.3231 +** * ON and USING clauses are shifted into WHERE statements
1.3232 +** * Wildcards "*" and "TABLE.*" in result sets are expanded.
1.3233 +** * Identifiers in expression are matched to tables.
1.3234 +**
1.3235 +** This routine acts recursively on all subqueries within the SELECT.
1.3236 +*/
1.3237 +void sqlite3SelectPrep(
1.3238 + Parse *pParse, /* The parser context */
1.3239 + Select *p, /* The SELECT statement being coded. */
1.3240 + NameContext *pOuterNC /* Name context for container */
1.3241 +){
1.3242 + sqlite3 *db;
1.3243 + if( p==0 ) return;
1.3244 + db = pParse->db;
1.3245 + if( p->selFlags & SF_HasTypeInfo ) return;
1.3246 + if( pParse->nErr || db->mallocFailed ) return;
1.3247 + sqlite3SelectExpand(pParse, p);
1.3248 + if( pParse->nErr || db->mallocFailed ) return;
1.3249 + sqlite3ResolveSelectNames(pParse, p, pOuterNC);
1.3250 + if( pParse->nErr || db->mallocFailed ) return;
1.3251 + sqlite3SelectAddTypeInfo(pParse, p);
1.3252 +}
1.3253 +
1.3254 +/*
1.3255 +** Reset the aggregate accumulator.
1.3256 +**
1.3257 +** The aggregate accumulator is a set of memory cells that hold
1.3258 +** intermediate results while calculating an aggregate. This
1.3259 +** routine simply stores NULLs in all of those memory cells.
1.3260 +*/
1.3261 +static void resetAccumulator(Parse *pParse, AggInfo *pAggInfo){
1.3262 + Vdbe *v = pParse->pVdbe;
1.3263 + int i;
1.3264 + struct AggInfo_func *pFunc;
1.3265 + if( pAggInfo->nFunc+pAggInfo->nColumn==0 ){
1.3266 + return;
1.3267 + }
1.3268 + for(i=0; i<pAggInfo->nColumn; i++){
1.3269 + sqlite3VdbeAddOp2(v, OP_Null, 0, pAggInfo->aCol[i].iMem);
1.3270 + }
1.3271 + for(pFunc=pAggInfo->aFunc, i=0; i<pAggInfo->nFunc; i++, pFunc++){
1.3272 + sqlite3VdbeAddOp2(v, OP_Null, 0, pFunc->iMem);
1.3273 + if( pFunc->iDistinct>=0 ){
1.3274 + Expr *pE = pFunc->pExpr;
1.3275 + if( pE->pList==0 || pE->pList->nExpr!=1 ){
1.3276 + sqlite3ErrorMsg(pParse, "DISTINCT in aggregate must be followed "
1.3277 + "by an expression");
1.3278 + pFunc->iDistinct = -1;
1.3279 + }else{
1.3280 + KeyInfo *pKeyInfo = keyInfoFromExprList(pParse, pE->pList);
1.3281 + sqlite3VdbeAddOp4(v, OP_OpenEphemeral, pFunc->iDistinct, 0, 0,
1.3282 + (char*)pKeyInfo, P4_KEYINFO_HANDOFF);
1.3283 + }
1.3284 + }
1.3285 + }
1.3286 +}
1.3287 +
1.3288 +/*
1.3289 +** Invoke the OP_AggFinalize opcode for every aggregate function
1.3290 +** in the AggInfo structure.
1.3291 +*/
1.3292 +static void finalizeAggFunctions(Parse *pParse, AggInfo *pAggInfo){
1.3293 + Vdbe *v = pParse->pVdbe;
1.3294 + int i;
1.3295 + struct AggInfo_func *pF;
1.3296 + for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){
1.3297 + ExprList *pList = pF->pExpr->pList;
1.3298 + sqlite3VdbeAddOp4(v, OP_AggFinal, pF->iMem, pList ? pList->nExpr : 0, 0,
1.3299 + (void*)pF->pFunc, P4_FUNCDEF);
1.3300 + }
1.3301 +}
1.3302 +
1.3303 +/*
1.3304 +** Update the accumulator memory cells for an aggregate based on
1.3305 +** the current cursor position.
1.3306 +*/
1.3307 +static void updateAccumulator(Parse *pParse, AggInfo *pAggInfo){
1.3308 + Vdbe *v = pParse->pVdbe;
1.3309 + int i;
1.3310 + struct AggInfo_func *pF;
1.3311 + struct AggInfo_col *pC;
1.3312 +
1.3313 + pAggInfo->directMode = 1;
1.3314 + for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){
1.3315 + int nArg;
1.3316 + int addrNext = 0;
1.3317 + int regAgg;
1.3318 + ExprList *pList = pF->pExpr->pList;
1.3319 + if( pList ){
1.3320 + nArg = pList->nExpr;
1.3321 + regAgg = sqlite3GetTempRange(pParse, nArg);
1.3322 + sqlite3ExprCodeExprList(pParse, pList, regAgg, 0);
1.3323 + }else{
1.3324 + nArg = 0;
1.3325 + regAgg = 0;
1.3326 + }
1.3327 + if( pF->iDistinct>=0 ){
1.3328 + addrNext = sqlite3VdbeMakeLabel(v);
1.3329 + assert( nArg==1 );
1.3330 + codeDistinct(pParse, pF->iDistinct, addrNext, 1, regAgg);
1.3331 + }
1.3332 + if( pF->pFunc->needCollSeq ){
1.3333 + CollSeq *pColl = 0;
1.3334 + struct ExprList_item *pItem;
1.3335 + int j;
1.3336 + assert( pList!=0 ); /* pList!=0 if pF->pFunc->needCollSeq is true */
1.3337 + for(j=0, pItem=pList->a; !pColl && j<nArg; j++, pItem++){
1.3338 + pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr);
1.3339 + }
1.3340 + if( !pColl ){
1.3341 + pColl = pParse->db->pDfltColl;
1.3342 + }
1.3343 + sqlite3VdbeAddOp4(v, OP_CollSeq, 0, 0, 0, (char *)pColl, P4_COLLSEQ);
1.3344 + }
1.3345 + sqlite3VdbeAddOp4(v, OP_AggStep, 0, regAgg, pF->iMem,
1.3346 + (void*)pF->pFunc, P4_FUNCDEF);
1.3347 + sqlite3VdbeChangeP5(v, nArg);
1.3348 + sqlite3ReleaseTempRange(pParse, regAgg, nArg);
1.3349 + sqlite3ExprCacheAffinityChange(pParse, regAgg, nArg);
1.3350 + if( addrNext ){
1.3351 + sqlite3VdbeResolveLabel(v, addrNext);
1.3352 + }
1.3353 + }
1.3354 + for(i=0, pC=pAggInfo->aCol; i<pAggInfo->nAccumulator; i++, pC++){
1.3355 + sqlite3ExprCode(pParse, pC->pExpr, pC->iMem);
1.3356 + }
1.3357 + pAggInfo->directMode = 0;
1.3358 +}
1.3359 +
1.3360 +/*
1.3361 +** Generate code for the SELECT statement given in the p argument.
1.3362 +**
1.3363 +** The results are distributed in various ways depending on the
1.3364 +** contents of the SelectDest structure pointed to by argument pDest
1.3365 +** as follows:
1.3366 +**
1.3367 +** pDest->eDest Result
1.3368 +** ------------ -------------------------------------------
1.3369 +** SRT_Output Generate a row of output (using the OP_ResultRow
1.3370 +** opcode) for each row in the result set.
1.3371 +**
1.3372 +** SRT_Mem Only valid if the result is a single column.
1.3373 +** Store the first column of the first result row
1.3374 +** in register pDest->iParm then abandon the rest
1.3375 +** of the query. This destination implies "LIMIT 1".
1.3376 +**
1.3377 +** SRT_Set The result must be a single column. Store each
1.3378 +** row of result as the key in table pDest->iParm.
1.3379 +** Apply the affinity pDest->affinity before storing
1.3380 +** results. Used to implement "IN (SELECT ...)".
1.3381 +**
1.3382 +** SRT_Union Store results as a key in a temporary table pDest->iParm.
1.3383 +**
1.3384 +** SRT_Except Remove results from the temporary table pDest->iParm.
1.3385 +**
1.3386 +** SRT_Table Store results in temporary table pDest->iParm.
1.3387 +** This is like SRT_EphemTab except that the table
1.3388 +** is assumed to already be open.
1.3389 +**
1.3390 +** SRT_EphemTab Create an temporary table pDest->iParm and store
1.3391 +** the result there. The cursor is left open after
1.3392 +** returning. This is like SRT_Table except that
1.3393 +** this destination uses OP_OpenEphemeral to create
1.3394 +** the table first.
1.3395 +**
1.3396 +** SRT_Coroutine Generate a co-routine that returns a new row of
1.3397 +** results each time it is invoked. The entry point
1.3398 +** of the co-routine is stored in register pDest->iParm.
1.3399 +**
1.3400 +** SRT_Exists Store a 1 in memory cell pDest->iParm if the result
1.3401 +** set is not empty.
1.3402 +**
1.3403 +** SRT_Discard Throw the results away. This is used by SELECT
1.3404 +** statements within triggers whose only purpose is
1.3405 +** the side-effects of functions.
1.3406 +**
1.3407 +** This routine returns the number of errors. If any errors are
1.3408 +** encountered, then an appropriate error message is left in
1.3409 +** pParse->zErrMsg.
1.3410 +**
1.3411 +** This routine does NOT free the Select structure passed in. The
1.3412 +** calling function needs to do that.
1.3413 +*/
1.3414 +int sqlite3Select(
1.3415 + Parse *pParse, /* The parser context */
1.3416 + Select *p, /* The SELECT statement being coded. */
1.3417 + SelectDest *pDest /* What to do with the query results */
1.3418 +){
1.3419 + int i, j; /* Loop counters */
1.3420 + WhereInfo *pWInfo; /* Return from sqlite3WhereBegin() */
1.3421 + Vdbe *v; /* The virtual machine under construction */
1.3422 + int isAgg; /* True for select lists like "count(*)" */
1.3423 + ExprList *pEList; /* List of columns to extract. */
1.3424 + SrcList *pTabList; /* List of tables to select from */
1.3425 + Expr *pWhere; /* The WHERE clause. May be NULL */
1.3426 + ExprList *pOrderBy; /* The ORDER BY clause. May be NULL */
1.3427 + ExprList *pGroupBy; /* The GROUP BY clause. May be NULL */
1.3428 + Expr *pHaving; /* The HAVING clause. May be NULL */
1.3429 + int isDistinct; /* True if the DISTINCT keyword is present */
1.3430 + int distinct; /* Table to use for the distinct set */
1.3431 + int rc = 1; /* Value to return from this function */
1.3432 + int addrSortIndex; /* Address of an OP_OpenEphemeral instruction */
1.3433 + AggInfo sAggInfo; /* Information used by aggregate queries */
1.3434 + int iEnd; /* Address of the end of the query */
1.3435 + sqlite3 *db; /* The database connection */
1.3436 +
1.3437 + db = pParse->db;
1.3438 + if( p==0 || db->mallocFailed || pParse->nErr ){
1.3439 + return 1;
1.3440 + }
1.3441 + if( sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0) ) return 1;
1.3442 + memset(&sAggInfo, 0, sizeof(sAggInfo));
1.3443 +
1.3444 + pOrderBy = p->pOrderBy;
1.3445 + if( IgnorableOrderby(pDest) ){
1.3446 + p->pOrderBy = 0;
1.3447 +
1.3448 + /* In these cases the DISTINCT operator makes no difference to the
1.3449 + ** results, so remove it if it were specified.
1.3450 + */
1.3451 + assert(pDest->eDest==SRT_Exists || pDest->eDest==SRT_Union ||
1.3452 + pDest->eDest==SRT_Except || pDest->eDest==SRT_Discard);
1.3453 + p->selFlags &= ~SF_Distinct;
1.3454 + }
1.3455 + sqlite3SelectPrep(pParse, p, 0);
1.3456 + if( pParse->nErr ){
1.3457 + goto select_end;
1.3458 + }
1.3459 + p->pOrderBy = pOrderBy;
1.3460 +
1.3461 +
1.3462 + /* Make local copies of the parameters for this query.
1.3463 + */
1.3464 + pTabList = p->pSrc;
1.3465 + isAgg = (p->selFlags & SF_Aggregate)!=0;
1.3466 + pEList = p->pEList;
1.3467 + if( pEList==0 ) goto select_end;
1.3468 +
1.3469 + /*
1.3470 + ** Do not even attempt to generate any code if we have already seen
1.3471 + ** errors before this routine starts.
1.3472 + */
1.3473 + if( pParse->nErr>0 ) goto select_end;
1.3474 +
1.3475 + /* ORDER BY is ignored for some destinations.
1.3476 + */
1.3477 + if( IgnorableOrderby(pDest) ){
1.3478 + pOrderBy = 0;
1.3479 + }
1.3480 +
1.3481 + /* Begin generating code.
1.3482 + */
1.3483 + v = sqlite3GetVdbe(pParse);
1.3484 + if( v==0 ) goto select_end;
1.3485 +
1.3486 + /* Generate code for all sub-queries in the FROM clause
1.3487 + */
1.3488 +#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
1.3489 + for(i=0; !p->pPrior && i<pTabList->nSrc; i++){
1.3490 + struct SrcList_item *pItem = &pTabList->a[i];
1.3491 + SelectDest dest;
1.3492 + Select *pSub = pItem->pSelect;
1.3493 + int isAggSub;
1.3494 +
1.3495 + if( pSub==0 || pItem->isPopulated ) continue;
1.3496 +
1.3497 + /* Increment Parse.nHeight by the height of the largest expression
1.3498 + ** tree refered to by this, the parent select. The child select
1.3499 + ** may contain expression trees of at most
1.3500 + ** (SQLITE_MAX_EXPR_DEPTH-Parse.nHeight) height. This is a bit
1.3501 + ** more conservative than necessary, but much easier than enforcing
1.3502 + ** an exact limit.
1.3503 + */
1.3504 + pParse->nHeight += sqlite3SelectExprHeight(p);
1.3505 +
1.3506 + /* Check to see if the subquery can be absorbed into the parent. */
1.3507 + isAggSub = (pSub->selFlags & SF_Aggregate)!=0;
1.3508 + if( flattenSubquery(pParse, p, i, isAgg, isAggSub) ){
1.3509 + if( isAggSub ){
1.3510 + isAgg = 1;
1.3511 + p->selFlags |= SF_Aggregate;
1.3512 + }
1.3513 + i = -1;
1.3514 + }else{
1.3515 + sqlite3SelectDestInit(&dest, SRT_EphemTab, pItem->iCursor);
1.3516 + assert( pItem->isPopulated==0 );
1.3517 + sqlite3Select(pParse, pSub, &dest);
1.3518 + pItem->isPopulated = 1;
1.3519 + }
1.3520 + if( pParse->nErr || db->mallocFailed ){
1.3521 + goto select_end;
1.3522 + }
1.3523 + pParse->nHeight -= sqlite3SelectExprHeight(p);
1.3524 + pTabList = p->pSrc;
1.3525 + if( !IgnorableOrderby(pDest) ){
1.3526 + pOrderBy = p->pOrderBy;
1.3527 + }
1.3528 + }
1.3529 + pEList = p->pEList;
1.3530 +#endif
1.3531 + pWhere = p->pWhere;
1.3532 + pGroupBy = p->pGroupBy;
1.3533 + pHaving = p->pHaving;
1.3534 + isDistinct = (p->selFlags & SF_Distinct)!=0;
1.3535 +
1.3536 +#ifndef SQLITE_OMIT_COMPOUND_SELECT
1.3537 + /* If there is are a sequence of queries, do the earlier ones first.
1.3538 + */
1.3539 + if( p->pPrior ){
1.3540 + if( p->pRightmost==0 ){
1.3541 + Select *pLoop, *pRight = 0;
1.3542 + int cnt = 0;
1.3543 + int mxSelect;
1.3544 + for(pLoop=p; pLoop; pLoop=pLoop->pPrior, cnt++){
1.3545 + pLoop->pRightmost = p;
1.3546 + pLoop->pNext = pRight;
1.3547 + pRight = pLoop;
1.3548 + }
1.3549 + mxSelect = db->aLimit[SQLITE_LIMIT_COMPOUND_SELECT];
1.3550 + if( mxSelect && cnt>mxSelect ){
1.3551 + sqlite3ErrorMsg(pParse, "too many terms in compound SELECT");
1.3552 + return 1;
1.3553 + }
1.3554 + }
1.3555 + return multiSelect(pParse, p, pDest);
1.3556 + }
1.3557 +#endif
1.3558 +
1.3559 + /* If writing to memory or generating a set
1.3560 + ** only a single column may be output.
1.3561 + */
1.3562 +#ifndef SQLITE_OMIT_SUBQUERY
1.3563 + if( checkForMultiColumnSelectError(pParse, pDest, pEList->nExpr) ){
1.3564 + goto select_end;
1.3565 + }
1.3566 +#endif
1.3567 +
1.3568 + /* If possible, rewrite the query to use GROUP BY instead of DISTINCT.
1.3569 + ** GROUP BY might use an index, DISTINCT never does.
1.3570 + */
1.3571 + if( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct && !p->pGroupBy ){
1.3572 + p->pGroupBy = sqlite3ExprListDup(db, p->pEList);
1.3573 + pGroupBy = p->pGroupBy;
1.3574 + p->selFlags &= ~SF_Distinct;
1.3575 + isDistinct = 0;
1.3576 + }
1.3577 +
1.3578 + /* If there is an ORDER BY clause, then this sorting
1.3579 + ** index might end up being unused if the data can be
1.3580 + ** extracted in pre-sorted order. If that is the case, then the
1.3581 + ** OP_OpenEphemeral instruction will be changed to an OP_Noop once
1.3582 + ** we figure out that the sorting index is not needed. The addrSortIndex
1.3583 + ** variable is used to facilitate that change.
1.3584 + */
1.3585 + if( pOrderBy ){
1.3586 + KeyInfo *pKeyInfo;
1.3587 + pKeyInfo = keyInfoFromExprList(pParse, pOrderBy);
1.3588 + pOrderBy->iECursor = pParse->nTab++;
1.3589 + p->addrOpenEphm[2] = addrSortIndex =
1.3590 + sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
1.3591 + pOrderBy->iECursor, pOrderBy->nExpr+2, 0,
1.3592 + (char*)pKeyInfo, P4_KEYINFO_HANDOFF);
1.3593 + }else{
1.3594 + addrSortIndex = -1;
1.3595 + }
1.3596 +
1.3597 + /* If the output is destined for a temporary table, open that table.
1.3598 + */
1.3599 + if( pDest->eDest==SRT_EphemTab ){
1.3600 + sqlite3VdbeAddOp2(v, OP_OpenEphemeral, pDest->iParm, pEList->nExpr);
1.3601 + }
1.3602 +
1.3603 + /* Set the limiter.
1.3604 + */
1.3605 + iEnd = sqlite3VdbeMakeLabel(v);
1.3606 + computeLimitRegisters(pParse, p, iEnd);
1.3607 +
1.3608 + /* Open a virtual index to use for the distinct set.
1.3609 + */
1.3610 + if( isDistinct ){
1.3611 + KeyInfo *pKeyInfo;
1.3612 + assert( isAgg || pGroupBy );
1.3613 + distinct = pParse->nTab++;
1.3614 + pKeyInfo = keyInfoFromExprList(pParse, p->pEList);
1.3615 + sqlite3VdbeAddOp4(v, OP_OpenEphemeral, distinct, 0, 0,
1.3616 + (char*)pKeyInfo, P4_KEYINFO_HANDOFF);
1.3617 + }else{
1.3618 + distinct = -1;
1.3619 + }
1.3620 +
1.3621 + /* Aggregate and non-aggregate queries are handled differently */
1.3622 + if( !isAgg && pGroupBy==0 ){
1.3623 + /* This case is for non-aggregate queries
1.3624 + ** Begin the database scan
1.3625 + */
1.3626 + pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pOrderBy, 0);
1.3627 + if( pWInfo==0 ) goto select_end;
1.3628 +
1.3629 + /* If sorting index that was created by a prior OP_OpenEphemeral
1.3630 + ** instruction ended up not being needed, then change the OP_OpenEphemeral
1.3631 + ** into an OP_Noop.
1.3632 + */
1.3633 + if( addrSortIndex>=0 && pOrderBy==0 ){
1.3634 + sqlite3VdbeChangeToNoop(v, addrSortIndex, 1);
1.3635 + p->addrOpenEphm[2] = -1;
1.3636 + }
1.3637 +
1.3638 + /* Use the standard inner loop
1.3639 + */
1.3640 + assert(!isDistinct);
1.3641 + selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, -1, pDest,
1.3642 + pWInfo->iContinue, pWInfo->iBreak);
1.3643 +
1.3644 + /* End the database scan loop.
1.3645 + */
1.3646 + sqlite3WhereEnd(pWInfo);
1.3647 + }else{
1.3648 + /* This is the processing for aggregate queries */
1.3649 + NameContext sNC; /* Name context for processing aggregate information */
1.3650 + int iAMem; /* First Mem address for storing current GROUP BY */
1.3651 + int iBMem; /* First Mem address for previous GROUP BY */
1.3652 + int iUseFlag; /* Mem address holding flag indicating that at least
1.3653 + ** one row of the input to the aggregator has been
1.3654 + ** processed */
1.3655 + int iAbortFlag; /* Mem address which causes query abort if positive */
1.3656 + int groupBySort; /* Rows come from source in GROUP BY order */
1.3657 + int addrEnd; /* End of processing for this SELECT */
1.3658 +
1.3659 + /* Remove any and all aliases between the result set and the
1.3660 + ** GROUP BY clause.
1.3661 + */
1.3662 + if( pGroupBy ){
1.3663 + int i; /* Loop counter */
1.3664 + struct ExprList_item *pItem; /* For looping over expression in a list */
1.3665 +
1.3666 + for(i=p->pEList->nExpr, pItem=p->pEList->a; i>0; i--, pItem++){
1.3667 + pItem->iAlias = 0;
1.3668 + }
1.3669 + for(i=pGroupBy->nExpr, pItem=pGroupBy->a; i>0; i--, pItem++){
1.3670 + pItem->iAlias = 0;
1.3671 + }
1.3672 + }
1.3673 +
1.3674 +
1.3675 + /* Create a label to jump to when we want to abort the query */
1.3676 + addrEnd = sqlite3VdbeMakeLabel(v);
1.3677 +
1.3678 + /* Convert TK_COLUMN nodes into TK_AGG_COLUMN and make entries in
1.3679 + ** sAggInfo for all TK_AGG_FUNCTION nodes in expressions of the
1.3680 + ** SELECT statement.
1.3681 + */
1.3682 + memset(&sNC, 0, sizeof(sNC));
1.3683 + sNC.pParse = pParse;
1.3684 + sNC.pSrcList = pTabList;
1.3685 + sNC.pAggInfo = &sAggInfo;
1.3686 + sAggInfo.nSortingColumn = pGroupBy ? pGroupBy->nExpr+1 : 0;
1.3687 + sAggInfo.pGroupBy = pGroupBy;
1.3688 + sqlite3ExprAnalyzeAggList(&sNC, pEList);
1.3689 + sqlite3ExprAnalyzeAggList(&sNC, pOrderBy);
1.3690 + if( pHaving ){
1.3691 + sqlite3ExprAnalyzeAggregates(&sNC, pHaving);
1.3692 + }
1.3693 + sAggInfo.nAccumulator = sAggInfo.nColumn;
1.3694 + for(i=0; i<sAggInfo.nFunc; i++){
1.3695 + sqlite3ExprAnalyzeAggList(&sNC, sAggInfo.aFunc[i].pExpr->pList);
1.3696 + }
1.3697 + if( db->mallocFailed ) goto select_end;
1.3698 +
1.3699 + /* Processing for aggregates with GROUP BY is very different and
1.3700 + ** much more complex than aggregates without a GROUP BY.
1.3701 + */
1.3702 + if( pGroupBy ){
1.3703 + KeyInfo *pKeyInfo; /* Keying information for the group by clause */
1.3704 + int j1; /* A-vs-B comparision jump */
1.3705 + int addrOutputRow; /* Start of subroutine that outputs a result row */
1.3706 + int regOutputRow; /* Return address register for output subroutine */
1.3707 + int addrSetAbort; /* Set the abort flag and return */
1.3708 + int addrTopOfLoop; /* Top of the input loop */
1.3709 + int addrSortingIdx; /* The OP_OpenEphemeral for the sorting index */
1.3710 + int addrReset; /* Subroutine for resetting the accumulator */
1.3711 + int regReset; /* Return address register for reset subroutine */
1.3712 +
1.3713 + /* If there is a GROUP BY clause we might need a sorting index to
1.3714 + ** implement it. Allocate that sorting index now. If it turns out
1.3715 + ** that we do not need it after all, the OpenEphemeral instruction
1.3716 + ** will be converted into a Noop.
1.3717 + */
1.3718 + sAggInfo.sortingIdx = pParse->nTab++;
1.3719 + pKeyInfo = keyInfoFromExprList(pParse, pGroupBy);
1.3720 + addrSortingIdx = sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
1.3721 + sAggInfo.sortingIdx, sAggInfo.nSortingColumn,
1.3722 + 0, (char*)pKeyInfo, P4_KEYINFO_HANDOFF);
1.3723 +
1.3724 + /* Initialize memory locations used by GROUP BY aggregate processing
1.3725 + */
1.3726 + iUseFlag = ++pParse->nMem;
1.3727 + iAbortFlag = ++pParse->nMem;
1.3728 + regOutputRow = ++pParse->nMem;
1.3729 + addrOutputRow = sqlite3VdbeMakeLabel(v);
1.3730 + regReset = ++pParse->nMem;
1.3731 + addrReset = sqlite3VdbeMakeLabel(v);
1.3732 + iAMem = pParse->nMem + 1;
1.3733 + pParse->nMem += pGroupBy->nExpr;
1.3734 + iBMem = pParse->nMem + 1;
1.3735 + pParse->nMem += pGroupBy->nExpr;
1.3736 + sqlite3VdbeAddOp2(v, OP_Integer, 0, iAbortFlag);
1.3737 + VdbeComment((v, "clear abort flag"));
1.3738 + sqlite3VdbeAddOp2(v, OP_Integer, 0, iUseFlag);
1.3739 + VdbeComment((v, "indicate accumulator empty"));
1.3740 +
1.3741 + /* Begin a loop that will extract all source rows in GROUP BY order.
1.3742 + ** This might involve two separate loops with an OP_Sort in between, or
1.3743 + ** it might be a single loop that uses an index to extract information
1.3744 + ** in the right order to begin with.
1.3745 + */
1.3746 + sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset);
1.3747 + pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pGroupBy, 0);
1.3748 + if( pWInfo==0 ) goto select_end;
1.3749 + if( pGroupBy==0 ){
1.3750 + /* The optimizer is able to deliver rows in group by order so
1.3751 + ** we do not have to sort. The OP_OpenEphemeral table will be
1.3752 + ** cancelled later because we still need to use the pKeyInfo
1.3753 + */
1.3754 + pGroupBy = p->pGroupBy;
1.3755 + groupBySort = 0;
1.3756 + }else{
1.3757 + /* Rows are coming out in undetermined order. We have to push
1.3758 + ** each row into a sorting index, terminate the first loop,
1.3759 + ** then loop over the sorting index in order to get the output
1.3760 + ** in sorted order
1.3761 + */
1.3762 + int regBase;
1.3763 + int regRecord;
1.3764 + int nCol;
1.3765 + int nGroupBy;
1.3766 +
1.3767 + groupBySort = 1;
1.3768 + nGroupBy = pGroupBy->nExpr;
1.3769 + nCol = nGroupBy + 1;
1.3770 + j = nGroupBy+1;
1.3771 + for(i=0; i<sAggInfo.nColumn; i++){
1.3772 + if( sAggInfo.aCol[i].iSorterColumn>=j ){
1.3773 + nCol++;
1.3774 + j++;
1.3775 + }
1.3776 + }
1.3777 + regBase = sqlite3GetTempRange(pParse, nCol);
1.3778 + sqlite3ExprCodeExprList(pParse, pGroupBy, regBase, 0);
1.3779 + sqlite3VdbeAddOp2(v, OP_Sequence, sAggInfo.sortingIdx,regBase+nGroupBy);
1.3780 + j = nGroupBy+1;
1.3781 + for(i=0; i<sAggInfo.nColumn; i++){
1.3782 + struct AggInfo_col *pCol = &sAggInfo.aCol[i];
1.3783 + if( pCol->iSorterColumn>=j ){
1.3784 + int r1 = j + regBase;
1.3785 + int r2;
1.3786 +
1.3787 + r2 = sqlite3ExprCodeGetColumn(pParse,
1.3788 + pCol->pTab, pCol->iColumn, pCol->iTable, r1, 0);
1.3789 + if( r1!=r2 ){
1.3790 + sqlite3VdbeAddOp2(v, OP_SCopy, r2, r1);
1.3791 + }
1.3792 + j++;
1.3793 + }
1.3794 + }
1.3795 + regRecord = sqlite3GetTempReg(pParse);
1.3796 + sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol, regRecord);
1.3797 + sqlite3VdbeAddOp2(v, OP_IdxInsert, sAggInfo.sortingIdx, regRecord);
1.3798 + sqlite3ReleaseTempReg(pParse, regRecord);
1.3799 + sqlite3ReleaseTempRange(pParse, regBase, nCol);
1.3800 + sqlite3WhereEnd(pWInfo);
1.3801 + sqlite3VdbeAddOp2(v, OP_Sort, sAggInfo.sortingIdx, addrEnd);
1.3802 + VdbeComment((v, "GROUP BY sort"));
1.3803 + sAggInfo.useSortingIdx = 1;
1.3804 + }
1.3805 +
1.3806 + /* Evaluate the current GROUP BY terms and store in b0, b1, b2...
1.3807 + ** (b0 is memory location iBMem+0, b1 is iBMem+1, and so forth)
1.3808 + ** Then compare the current GROUP BY terms against the GROUP BY terms
1.3809 + ** from the previous row currently stored in a0, a1, a2...
1.3810 + */
1.3811 + addrTopOfLoop = sqlite3VdbeCurrentAddr(v);
1.3812 + for(j=0; j<pGroupBy->nExpr; j++){
1.3813 + if( groupBySort ){
1.3814 + sqlite3VdbeAddOp3(v, OP_Column, sAggInfo.sortingIdx, j, iBMem+j);
1.3815 + }else{
1.3816 + sAggInfo.directMode = 1;
1.3817 + sqlite3ExprCode(pParse, pGroupBy->a[j].pExpr, iBMem+j);
1.3818 + }
1.3819 + }
1.3820 + sqlite3VdbeAddOp4(v, OP_Compare, iAMem, iBMem, pGroupBy->nExpr,
1.3821 + (char*)pKeyInfo, P4_KEYINFO);
1.3822 + j1 = sqlite3VdbeCurrentAddr(v);
1.3823 + sqlite3VdbeAddOp3(v, OP_Jump, j1+1, 0, j1+1);
1.3824 +
1.3825 + /* Generate code that runs whenever the GROUP BY changes.
1.3826 + ** Changes in the GROUP BY are detected by the previous code
1.3827 + ** block. If there were no changes, this block is skipped.
1.3828 + **
1.3829 + ** This code copies current group by terms in b0,b1,b2,...
1.3830 + ** over to a0,a1,a2. It then calls the output subroutine
1.3831 + ** and resets the aggregate accumulator registers in preparation
1.3832 + ** for the next GROUP BY batch.
1.3833 + */
1.3834 + sqlite3ExprCodeMove(pParse, iBMem, iAMem, pGroupBy->nExpr);
1.3835 + sqlite3VdbeAddOp2(v, OP_Gosub, regOutputRow, addrOutputRow);
1.3836 + VdbeComment((v, "output one row"));
1.3837 + sqlite3VdbeAddOp2(v, OP_IfPos, iAbortFlag, addrEnd);
1.3838 + VdbeComment((v, "check abort flag"));
1.3839 + sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset);
1.3840 + VdbeComment((v, "reset accumulator"));
1.3841 +
1.3842 + /* Update the aggregate accumulators based on the content of
1.3843 + ** the current row
1.3844 + */
1.3845 + sqlite3VdbeJumpHere(v, j1);
1.3846 + updateAccumulator(pParse, &sAggInfo);
1.3847 + sqlite3VdbeAddOp2(v, OP_Integer, 1, iUseFlag);
1.3848 + VdbeComment((v, "indicate data in accumulator"));
1.3849 +
1.3850 + /* End of the loop
1.3851 + */
1.3852 + if( groupBySort ){
1.3853 + sqlite3VdbeAddOp2(v, OP_Next, sAggInfo.sortingIdx, addrTopOfLoop);
1.3854 + }else{
1.3855 + sqlite3WhereEnd(pWInfo);
1.3856 + sqlite3VdbeChangeToNoop(v, addrSortingIdx, 1);
1.3857 + }
1.3858 +
1.3859 + /* Output the final row of result
1.3860 + */
1.3861 + sqlite3VdbeAddOp2(v, OP_Gosub, regOutputRow, addrOutputRow);
1.3862 + VdbeComment((v, "output final row"));
1.3863 +
1.3864 + /* Jump over the subroutines
1.3865 + */
1.3866 + sqlite3VdbeAddOp2(v, OP_Goto, 0, addrEnd);
1.3867 +
1.3868 + /* Generate a subroutine that outputs a single row of the result
1.3869 + ** set. This subroutine first looks at the iUseFlag. If iUseFlag
1.3870 + ** is less than or equal to zero, the subroutine is a no-op. If
1.3871 + ** the processing calls for the query to abort, this subroutine
1.3872 + ** increments the iAbortFlag memory location before returning in
1.3873 + ** order to signal the caller to abort.
1.3874 + */
1.3875 + addrSetAbort = sqlite3VdbeCurrentAddr(v);
1.3876 + sqlite3VdbeAddOp2(v, OP_Integer, 1, iAbortFlag);
1.3877 + VdbeComment((v, "set abort flag"));
1.3878 + sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
1.3879 + sqlite3VdbeResolveLabel(v, addrOutputRow);
1.3880 + addrOutputRow = sqlite3VdbeCurrentAddr(v);
1.3881 + sqlite3VdbeAddOp2(v, OP_IfPos, iUseFlag, addrOutputRow+2);
1.3882 + VdbeComment((v, "Groupby result generator entry point"));
1.3883 + sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
1.3884 + finalizeAggFunctions(pParse, &sAggInfo);
1.3885 + if( pHaving ){
1.3886 + sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, SQLITE_JUMPIFNULL);
1.3887 + }
1.3888 + selectInnerLoop(pParse, p, p->pEList, 0, 0, pOrderBy,
1.3889 + distinct, pDest,
1.3890 + addrOutputRow+1, addrSetAbort);
1.3891 + sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
1.3892 + VdbeComment((v, "end groupby result generator"));
1.3893 +
1.3894 + /* Generate a subroutine that will reset the group-by accumulator
1.3895 + */
1.3896 + sqlite3VdbeResolveLabel(v, addrReset);
1.3897 + resetAccumulator(pParse, &sAggInfo);
1.3898 + sqlite3VdbeAddOp1(v, OP_Return, regReset);
1.3899 +
1.3900 + } /* endif pGroupBy */
1.3901 + else {
1.3902 + ExprList *pMinMax = 0;
1.3903 + ExprList *pDel = 0;
1.3904 + u8 flag;
1.3905 +
1.3906 + /* Check if the query is of one of the following forms:
1.3907 + **
1.3908 + ** SELECT min(x) FROM ...
1.3909 + ** SELECT max(x) FROM ...
1.3910 + **
1.3911 + ** If it is, then ask the code in where.c to attempt to sort results
1.3912 + ** as if there was an "ORDER ON x" or "ORDER ON x DESC" clause.
1.3913 + ** If where.c is able to produce results sorted in this order, then
1.3914 + ** add vdbe code to break out of the processing loop after the
1.3915 + ** first iteration (since the first iteration of the loop is
1.3916 + ** guaranteed to operate on the row with the minimum or maximum
1.3917 + ** value of x, the only row required).
1.3918 + **
1.3919 + ** A special flag must be passed to sqlite3WhereBegin() to slightly
1.3920 + ** modify behaviour as follows:
1.3921 + **
1.3922 + ** + If the query is a "SELECT min(x)", then the loop coded by
1.3923 + ** where.c should not iterate over any values with a NULL value
1.3924 + ** for x.
1.3925 + **
1.3926 + ** + The optimizer code in where.c (the thing that decides which
1.3927 + ** index or indices to use) should place a different priority on
1.3928 + ** satisfying the 'ORDER BY' clause than it does in other cases.
1.3929 + ** Refer to code and comments in where.c for details.
1.3930 + */
1.3931 + flag = minMaxQuery(pParse, p);
1.3932 + if( flag ){
1.3933 + pDel = pMinMax = sqlite3ExprListDup(db, p->pEList->a[0].pExpr->pList);
1.3934 + if( pMinMax && !db->mallocFailed ){
1.3935 + pMinMax->a[0].sortOrder = flag!=WHERE_ORDERBY_MIN;
1.3936 + pMinMax->a[0].pExpr->op = TK_COLUMN;
1.3937 + }
1.3938 + }
1.3939 +
1.3940 + /* This case runs if the aggregate has no GROUP BY clause. The
1.3941 + ** processing is much simpler since there is only a single row
1.3942 + ** of output.
1.3943 + */
1.3944 + resetAccumulator(pParse, &sAggInfo);
1.3945 + pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pMinMax, flag);
1.3946 + if( pWInfo==0 ){
1.3947 + sqlite3ExprListDelete(db, pDel);
1.3948 + goto select_end;
1.3949 + }
1.3950 + updateAccumulator(pParse, &sAggInfo);
1.3951 + if( !pMinMax && flag ){
1.3952 + sqlite3VdbeAddOp2(v, OP_Goto, 0, pWInfo->iBreak);
1.3953 + VdbeComment((v, "%s() by index",(flag==WHERE_ORDERBY_MIN?"min":"max")));
1.3954 + }
1.3955 + sqlite3WhereEnd(pWInfo);
1.3956 + finalizeAggFunctions(pParse, &sAggInfo);
1.3957 + pOrderBy = 0;
1.3958 + if( pHaving ){
1.3959 + sqlite3ExprIfFalse(pParse, pHaving, addrEnd, SQLITE_JUMPIFNULL);
1.3960 + }
1.3961 + selectInnerLoop(pParse, p, p->pEList, 0, 0, 0, -1,
1.3962 + pDest, addrEnd, addrEnd);
1.3963 +
1.3964 + sqlite3ExprListDelete(db, pDel);
1.3965 + }
1.3966 + sqlite3VdbeResolveLabel(v, addrEnd);
1.3967 +
1.3968 + } /* endif aggregate query */
1.3969 +
1.3970 + /* If there is an ORDER BY clause, then we need to sort the results
1.3971 + ** and send them to the callback one by one.
1.3972 + */
1.3973 + if( pOrderBy ){
1.3974 + generateSortTail(pParse, p, v, pEList->nExpr, pDest);
1.3975 + }
1.3976 +
1.3977 + /* Jump here to skip this query
1.3978 + */
1.3979 + sqlite3VdbeResolveLabel(v, iEnd);
1.3980 +
1.3981 + /* The SELECT was successfully coded. Set the return code to 0
1.3982 + ** to indicate no errors.
1.3983 + */
1.3984 + rc = 0;
1.3985 +
1.3986 + /* Control jumps to here if an error is encountered above, or upon
1.3987 + ** successful coding of the SELECT.
1.3988 + */
1.3989 +select_end:
1.3990 +
1.3991 + /* Identify column names if results of the SELECT are to be output.
1.3992 + */
1.3993 + if( rc==SQLITE_OK && pDest->eDest==SRT_Output ){
1.3994 + generateColumnNames(pParse, pTabList, pEList);
1.3995 + }
1.3996 +
1.3997 + sqlite3DbFree(db, sAggInfo.aCol);
1.3998 + sqlite3DbFree(db, sAggInfo.aFunc);
1.3999 + return rc;
1.4000 +}
1.4001 +
1.4002 +#if defined(SQLITE_DEBUG)
1.4003 +/*
1.4004 +*******************************************************************************
1.4005 +** The following code is used for testing and debugging only. The code
1.4006 +** that follows does not appear in normal builds.
1.4007 +**
1.4008 +** These routines are used to print out the content of all or part of a
1.4009 +** parse structures such as Select or Expr. Such printouts are useful
1.4010 +** for helping to understand what is happening inside the code generator
1.4011 +** during the execution of complex SELECT statements.
1.4012 +**
1.4013 +** These routine are not called anywhere from within the normal
1.4014 +** code base. Then are intended to be called from within the debugger
1.4015 +** or from temporary "printf" statements inserted for debugging.
1.4016 +*/
1.4017 +void sqlite3PrintExpr(Expr *p){
1.4018 + if( p->token.z && p->token.n>0 ){
1.4019 + sqlite3DebugPrintf("(%.*s", p->token.n, p->token.z);
1.4020 + }else{
1.4021 + sqlite3DebugPrintf("(%d", p->op);
1.4022 + }
1.4023 + if( p->pLeft ){
1.4024 + sqlite3DebugPrintf(" ");
1.4025 + sqlite3PrintExpr(p->pLeft);
1.4026 + }
1.4027 + if( p->pRight ){
1.4028 + sqlite3DebugPrintf(" ");
1.4029 + sqlite3PrintExpr(p->pRight);
1.4030 + }
1.4031 + sqlite3DebugPrintf(")");
1.4032 +}
1.4033 +void sqlite3PrintExprList(ExprList *pList){
1.4034 + int i;
1.4035 + for(i=0; i<pList->nExpr; i++){
1.4036 + sqlite3PrintExpr(pList->a[i].pExpr);
1.4037 + if( i<pList->nExpr-1 ){
1.4038 + sqlite3DebugPrintf(", ");
1.4039 + }
1.4040 + }
1.4041 +}
1.4042 +void sqlite3PrintSelect(Select *p, int indent){
1.4043 + sqlite3DebugPrintf("%*sSELECT(%p) ", indent, "", p);
1.4044 + sqlite3PrintExprList(p->pEList);
1.4045 + sqlite3DebugPrintf("\n");
1.4046 + if( p->pSrc ){
1.4047 + char *zPrefix;
1.4048 + int i;
1.4049 + zPrefix = "FROM";
1.4050 + for(i=0; i<p->pSrc->nSrc; i++){
1.4051 + struct SrcList_item *pItem = &p->pSrc->a[i];
1.4052 + sqlite3DebugPrintf("%*s ", indent+6, zPrefix);
1.4053 + zPrefix = "";
1.4054 + if( pItem->pSelect ){
1.4055 + sqlite3DebugPrintf("(\n");
1.4056 + sqlite3PrintSelect(pItem->pSelect, indent+10);
1.4057 + sqlite3DebugPrintf("%*s)", indent+8, "");
1.4058 + }else if( pItem->zName ){
1.4059 + sqlite3DebugPrintf("%s", pItem->zName);
1.4060 + }
1.4061 + if( pItem->pTab ){
1.4062 + sqlite3DebugPrintf("(table: %s)", pItem->pTab->zName);
1.4063 + }
1.4064 + if( pItem->zAlias ){
1.4065 + sqlite3DebugPrintf(" AS %s", pItem->zAlias);
1.4066 + }
1.4067 + if( i<p->pSrc->nSrc-1 ){
1.4068 + sqlite3DebugPrintf(",");
1.4069 + }
1.4070 + sqlite3DebugPrintf("\n");
1.4071 + }
1.4072 + }
1.4073 + if( p->pWhere ){
1.4074 + sqlite3DebugPrintf("%*s WHERE ", indent, "");
1.4075 + sqlite3PrintExpr(p->pWhere);
1.4076 + sqlite3DebugPrintf("\n");
1.4077 + }
1.4078 + if( p->pGroupBy ){
1.4079 + sqlite3DebugPrintf("%*s GROUP BY ", indent, "");
1.4080 + sqlite3PrintExprList(p->pGroupBy);
1.4081 + sqlite3DebugPrintf("\n");
1.4082 + }
1.4083 + if( p->pHaving ){
1.4084 + sqlite3DebugPrintf("%*s HAVING ", indent, "");
1.4085 + sqlite3PrintExpr(p->pHaving);
1.4086 + sqlite3DebugPrintf("\n");
1.4087 + }
1.4088 + if( p->pOrderBy ){
1.4089 + sqlite3DebugPrintf("%*s ORDER BY ", indent, "");
1.4090 + sqlite3PrintExprList(p->pOrderBy);
1.4091 + sqlite3DebugPrintf("\n");
1.4092 + }
1.4093 +}
1.4094 +/* End of the structure debug printing code
1.4095 +*****************************************************************************/
1.4096 +#endif /* defined(SQLITE_TEST) || defined(SQLITE_DEBUG) */