test/null.test

# 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}

# 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
#
do_test null-6.1 {
  execsql {
    select b from t1 union select c from t1 order by c;
  }
} {{} 0 1}

# The UNIQUE constraint only applies to non-null values
#
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}



finish_test