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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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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