# 2001 September 15

 #

 # The author disclaims copyright to this source code.  In place of

 # a legal notice, here is a blessing:

 #

 #    May you do good and not evil.

 #    May you find forgiveness for yourself and forgive others.

 #    May you share freely, never taking more than you give.

 #

 #***********************************************************************

 # This file implements regression tests for SQLite library.

 #

 # This file implements tests for proper treatment of the special

 # value NULL.

 #

 set testdir [file dirname $argv0]

 source $testdir/tester.tcl

 # Create a table and some data to work with.

 #

 do_test null-1.0 {

   execsql {

     begin;

     create table t1(a,b,c);

     insert into t1 values(1,0,0);

     insert into t1 values(2,0,1);

     insert into t1 values(3,1,0);

     insert into t1 values(4,1,1);

     insert into t1 values(5,null,0);

     insert into t1 values(6,null,1);

     insert into t1 values(7,null,null);

     commit;

     select * from t1;

   }

 } {1 0 0 2 0 1 3 1 0 4 1 1 5 {} 0 6 {} 1 7 {} {}}

 # Check for how arithmetic expressions handle NULL

 #

 do_test null-1.1 {

   execsql {

     select ifnull(a+b,99) from t1;

   }

 } {1 2 4 5 99 99 99}

 do_test null-1.2 {

   execsql {

     select ifnull(b*c,99) from t1;

   }

 } {0 0 0 1 99 99 99}

 # Check to see how the CASE expression handles NULL values.  The

 # first WHEN for which the test expression is TRUE is selected.

 # FALSE and UNKNOWN test expressions are skipped.

 #

 do_test null-2.1 {

   execsql {

     select ifnull(case when b<>0 then 1 else 0 end, 99) from t1;

   }

 } {0 0 1 1 0 0 0}

 do_test null-2.2 {

   execsql {

     select ifnull(case when not b<>0 then 1 else 0 end, 99) from t1;

   }

 } {1 1 0 0 0 0 0}

 do_test null-2.3 {

   execsql {

     select ifnull(case when b<>0 and c<>0 then 1 else 0 end, 99) from t1;

   }

 } {0 0 0 1 0 0 0}

 do_test null-2.4 {

   execsql {

     select ifnull(case when not (b<>0 and c<>0) then 1 else 0 end, 99) from t1;

   }

 } {1 1 1 0 1 0 0}

 do_test null-2.5 {

   execsql {

     select ifnull(case when b<>0 or c<>0 then 1 else 0 end, 99) from t1;

   }

 } {0 1 1 1 0 1 0}

 do_test null-2.6 {

   execsql {

     select ifnull(case when not (b<>0 or c<>0) then 1 else 0 end, 99) from t1;

   }

 } {1 0 0 0 0 0 0}

 do_test null-2.7 {

   execsql {

     select ifnull(case b when c then 1 else 0 end, 99) from t1;

   }

 } {1 0 0 1 0 0 0}

 do_test null-2.8 {

   execsql {

     select ifnull(case c when b then 1 else 0 end, 99) from t1;

   }

 } {1 0 0 1 0 0 0}

 # Check to see that NULL values are ignored in aggregate functions.

 #

 do_test null-3.1 {

   execsql {

     select count(*), count(b), count(c), sum(b), sum(c), 

            avg(b), avg(c), min(b), max(b) from t1;

   }

 } {7 4 6 2 3 0.5 0.5 0 1}

 # The sum of zero entries is a NULL, but the total of zero entries is 0.

 #

 do_test null-3.2 {

   execsql {

     SELECT sum(b), total(b) FROM t1 WHERE b<0

   }

 } {{} 0.0}

 # Check to see how WHERE clauses handle NULL values.  A NULL value

 # is the same as UNKNOWN.  The WHERE clause should only select those

 # rows that are TRUE.  FALSE and UNKNOWN rows are rejected.

 #

 do_test null-4.1 {

   execsql {

     select a from t1 where b<10

   }

 } {1 2 3 4}

 do_test null-4.2 {

   execsql {

     select a from t1 where not b>10

   }

 } {1 2 3 4}

 do_test null-4.3 {

   execsql {

     select a from t1 where b<10 or c=1;

   }

 } {1 2 3 4 6}

 do_test null-4.4 {

   execsql {

     select a from t1 where b<10 and c=1;

   }

 } {2 4}

 do_test null-4.5 {

   execsql {

     select a from t1 where not (b<10 and c=1);

   }

 } {1 3 5}

 # The DISTINCT keyword on a SELECT statement should treat NULL values

 # as distinct

 #

 do_test null-5.1 {

   execsql {

     select distinct b from t1 order by b;

   }

 } {{} 0 1}

 # A UNION to two queries should treat NULL values

 # as distinct.

 #

 # (Later:)  We also take this opportunity to test the ability

 # of an ORDER BY clause to bind to either SELECT of a UNION.

 # The left-most SELECT is preferred.  In standard SQL, only

 # the left SELECT can be used.  The ability to match an ORDER

 # BY term to the right SELECT is an SQLite extension.

 #

 ifcapable compound {

   do_test null-6.1 {

     execsql {

       select b from t1 union select c from t1 order by b;

     }

   } {{} 0 1}

   do_test null-6.2 {

     execsql {

       select b from t1 union select c from t1 order by 1;

     }

   } {{} 0 1}

   do_test null-6.3 {

     execsql {

       select b from t1 union select c from t1 order by t1.b;

     }

   } {{} 0 1}

   do_test null-6.4 {

     execsql {

       select b from t1 union select c from t1 order by main.t1.b;

     }

   } {{} 0 1}

   do_test null-6.5 {

     catchsql {

       select b from t1 union select c from t1 order by t1.a;

     }

   } {1 {1st ORDER BY term does not match any column in the result set}}

   do_test null-6.6 {

     catchsql {

       select b from t1 union select c from t1 order by main.t1.a;

     }

   } {1 {1st ORDER BY term does not match any column in the result set}}

 } ;# ifcapable compound

 # The UNIQUE constraint only applies to non-null values

 #

 ifcapable conflict {

 do_test null-7.1 {

     execsql {

       create table t2(a, b unique on conflict ignore);

       insert into t2 values(1,1);

       insert into t2 values(2,null);

       insert into t2 values(3,null);

       insert into t2 values(4,1);

       select a from t2;

     }

   } {1 2 3}

   do_test null-7.2 {

     execsql {

       create table t3(a, b, c, unique(b,c) on conflict ignore);

       insert into t3 values(1,1,1);

       insert into t3 values(2,null,1);

       insert into t3 values(3,null,1);

       insert into t3 values(4,1,1);

       select a from t3;

     }

   } {1 2 3}

 }

 # Ticket #461 - Make sure nulls are handled correctly when doing a

 # lookup using an index.

 #

 do_test null-8.1 {

   execsql {

     CREATE TABLE t4(x,y);

     INSERT INTO t4 VALUES(1,11);

     INSERT INTO t4 VALUES(2,NULL);

     SELECT x FROM t4 WHERE y=NULL;

   }

 } {}

 ifcapable subquery {

   do_test null-8.2 {

     execsql {

       SELECT x FROM t4 WHERE y IN (33,NULL);

     }

   } {}

 }

 do_test null-8.3 {

   execsql {

     SELECT x FROM t4 WHERE y<33 ORDER BY x;

   }

 } {1}

 do_test null-8.4 {

   execsql {

     SELECT x FROM t4 WHERE y>6 ORDER BY x;

   }

 } {1}

 do_test null-8.5 {

   execsql {

     SELECT x FROM t4 WHERE y!=33 ORDER BY x;

   }

 } {1}

 do_test null-8.11 {

   execsql {

     CREATE INDEX t4i1 ON t4(y);

     SELECT x FROM t4 WHERE y=NULL;

   }

 } {}

 ifcapable subquery {

   do_test null-8.12 {

     execsql {

       SELECT x FROM t4 WHERE y IN (33,NULL);

     }

   } {}

 }

 do_test null-8.13 {

   execsql {

     SELECT x FROM t4 WHERE y<33 ORDER BY x;

   }

 } {1}

 do_test null-8.14 {

   execsql {

     SELECT x FROM t4 WHERE y>6 ORDER BY x;

   }

 } {1}

 do_test null-8.15 {

   execsql {

     SELECT x FROM t4 WHERE y!=33 ORDER BY x;

   }

 } {1}

 finish_test