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Refinements to NULL processing: NULLs are indistinct for DISTINCT and UNION.

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Multiplying a NULL by zero yields zero. In a CASE expression, a NULL comparison
is considered false, not NULL.  With these changes, NULLs in SQLite now work
the same as in PostgreSQL and in Oracle. (CVS 600)

FossilOrigin-Name: da61aa1d238539dff9c43fd9f464d311e28d669f
This commit is contained in:
drh
2002-05-31 15:51:25 +00:00
parent 0f89253e21
commit f570f011eb
11 changed files with 279 additions and 59 deletions
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12
test/expr.test
View File

@ -11,7 +11,7 @@
# This file implements regression tests for SQLite library. The
# focus of this file is testing expressions.
#
# $Id: expr.test,v 1.23 2002/05/30 12:27:03 drh Exp $
# $Id: expr.test,v 1.24 2002/05/31 15:51:26 drh Exp $
set testdir [file dirname $argv0]
source $testdir/tester.tcl
@ -337,23 +337,23 @@ test_expr expr-case.1 {i1=1, i2=2} \
test_expr expr-case.2 {i1=2, i2=2} \
{CASE WHEN i1 = i2 THEN 'eq' ELSE 'ne' END} eq
test_expr expr-case.3 {i1=NULL, i2=2} \
{CASE WHEN i1 = i2 THEN 'eq' ELSE 'ne' END} {{}}
{CASE WHEN i1 = i2 THEN 'eq' ELSE 'ne' END} ne
test_expr expr-case.4 {i1=2, i2=NULL} \
{CASE WHEN i1 = i2 THEN 'eq' ELSE 'ne' END} {{}}
{CASE WHEN i1 = i2 THEN 'eq' ELSE 'ne' END} ne
test_expr expr-case.5 {i1=2} \
{CASE i1 WHEN 1 THEN 'one' WHEN 2 THEN 'two' ELSE 'error' END} two
test_expr expr-case.6 {i1=1} \
{CASE i1 WHEN 1 THEN 'one' WHEN NULL THEN 'two' ELSE 'error' END} one
test_expr expr-case.7 {i1=2} \
{CASE i1 WHEN 1 THEN 'one' WHEN NULL THEN 'two' ELSE 'error' END} {{}}
{CASE i1 WHEN 1 THEN 'one' WHEN NULL THEN 'two' ELSE 'error' END} error
test_expr expr-case.8 {i1=3} \
{CASE i1 WHEN 1 THEN 'one' WHEN NULL THEN 'two' ELSE 'error' END} {{}}
{CASE i1 WHEN 1 THEN 'one' WHEN NULL THEN 'two' ELSE 'error' END} error
test_expr expr-case.9 {i1=3} \
{CASE i1 WHEN 1 THEN 'one' WHEN 2 THEN 'two' ELSE 'error' END} error
test_expr expr-case.10 {i1=3} \
{CASE i1 WHEN 1 THEN 'one' WHEN 2 THEN 'two' END} {{}}
test_expr expr-case.11 {i1=null} \
{CASE i1 WHEN 1 THEN 'one' WHEN 2 THEN 'two' ELSE 3 END} {{}}
{CASE i1 WHEN 1 THEN 'one' WHEN 2 THEN 'two' ELSE 3 END} 3
test_expr expr-case.12 {i1=1} \
{CASE i1 WHEN 1 THEN null WHEN 2 THEN 'two' ELSE 3 END} {{}}
test_expr expr-case.13 {i1=7} \

16
test/minmax.test
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@ -13,7 +13,7 @@
# aggregate min() and max() functions and which are handled as
# as a special case.
#
# $Id: minmax.test,v 1.3 2002/05/29 23:22:23 drh Exp $
# $Id: minmax.test,v 1.4 2002/05/31 15:51:26 drh Exp $
set testdir [file dirname $argv0]
source $testdir/tester.tcl
@ -128,5 +128,19 @@ do_test minmax-4.1 {
(SELECT * FROM t1 UNION SELECT NULL as 'x', NULL as 'y')
}
} {1 20}
do_test minmax-4.2 {
execsql {
SELECT y, sum(x) FROM
(SELECT null, y+1 FROM t1 UNION SELECT * FROM t1)
GROUP BY y ORDER BY y;
}
} {1 1 2 5 3 22 4 92 5 90 6 0}
do_test minmax-4.3 {
execsql {
SELECT y, count(x), count(*) FROM
(SELECT null, y+1 FROM t1 UNION SELECT * FROM t1)
GROUP BY y ORDER BY y;
}
} {1 1 1 2 2 3 3 4 5 4 8 9 5 5 6 6 0 1}
finish_test

183
test/null.test Normal file
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@ -0,0 +1,183 @@
# 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 0 99 99}
do_test null-1.2.1 {
execsql {
select ifnull(c*b,99) from t1;
}
} {0 0 0 1 0 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

15
test/select4.test
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@ -12,7 +12,7 @@
# focus of this file is testing UNION, INTERSECT and EXCEPT operators
# in SELECT statements.
#
# $Id: select4.test,v 1.8 2002/05/27 01:04:51 drh Exp $
# $Id: select4.test,v 1.9 2002/05/31 15:51:26 drh Exp $
set testdir [file dirname $argv0]
source $testdir/tester.tcl
@ -249,7 +249,8 @@ do_test select4-6.2 {
}
} {0 1 1 1 2 2 3 4 3 7 4 8 5 15}
# NULLs are distinct. Make sure the UNION operator recognizes this
# NULLs are indistinct for the UNION operator.
# Make sure the UNION operator recognizes this
#
do_test select4-6.3 {
execsql {
@ -257,8 +258,8 @@ do_test select4-6.3 {
SELECT 1 UNION SELECT 2 AS 'x'
ORDER BY x;
}
} {{} {} 1 2}
do_test select4-6.3 {
} {{} 1 2}
do_test select4-6.3.1 {
execsql {
SELECT NULL UNION ALL SELECT NULL UNION ALL
SELECT 1 UNION ALL SELECT 2 AS 'x'
@ -266,7 +267,7 @@ do_test select4-6.3 {
}
} {{} {} 1 2}
# Make sure the DISTINCT keyword treats NULLs as DISTINCT
# Make sure the DISTINCT keyword treats NULLs as indistinct.
#
do_test select4-6.4 {
execsql {
@ -281,7 +282,7 @@ do_test select4-6.5 {
SELECT NULL, 1 UNION ALL SELECT NULL, 1
);
}
} {{} 1 {} 1}
} {{} 1}
do_test select4-6.6 {
execsql {
SELECT DISTINCT * FROM (
@ -296,7 +297,7 @@ do_test select4-6.7 {
execsql {
SELECT NULL EXCEPT SELECT NULL
}
} {{}}
} {}
# Make sure column names are correct when a compound select appears as