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MDEV-7759 NULLIF(x,y) is not equal to CASE WHEN x=y THEN NULL ELSE x END

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This commit is contained in:
Alexander Barkov 2015-03-12 11:40:37 +04:00
parent 80f03abcca
commit e91bc2e91d
5 changed files with 93 additions and 32 deletions
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40
mysql-test/r/null.result
View file

@ -502,6 +502,10 @@ NULLIF(TIMESTAMP'2001-01-01 00:00:00',1.0),
NULLIF(TIMESTAMP'2001-01-01 00:00:00',1e0),
NULLIF(TIMESTAMP'2001-01-01 00:00:00','2001-01-01'),
NULLIF(TIMESTAMP'2001-01-01 00:00:00',TIME'00:00:00');
Warnings:
Warning 1292 Incorrect datetime value: '1'
Warning 1292 Incorrect datetime value: '1.0'
Warning 1292 Incorrect datetime value: '1'
SHOW CREATE TABLE t1;
Table Create Table
t1 CREATE TABLE `t1` (
@ -518,6 +522,10 @@ NULLIF(DATE'2001-01-01',1.0),
NULLIF(DATE'2001-01-01',1e0),
NULLIF(DATE'2001-01-01','2001-01-01'),
NULLIF(DATE'2001-01-01',TIME'00:00:00');
Warnings:
Warning 1292 Incorrect datetime value: '1'
Warning 1292 Incorrect datetime value: '1.0'
Warning 1292 Incorrect datetime value: '1'
SHOW CREATE TABLE t1;
Table Create Table
t1 CREATE TABLE `t1` (
@ -1350,5 +1358,37 @@ t2 CREATE TABLE `t2` (
DROP TABLE t2;
DROP TABLE t1;
#
# MDEV-7759 NULLIF(x,y) is not equal to CASE WHEN x=y THEN NULL ELSE x END
#
CREATE TABLE t1 (a YEAR);
INSERT INTO t1 VALUES (2010),(2020);
SELECT * FROM t1 WHERE a=2010 AND NULLIF(10.1,a) IS NULL;
a
2010
EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=2010 AND NULLIF(10.1,a) IS NULL;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 2 100.00 Using where
Warnings:
Note 1003 select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((`test`.`t1`.`a` = 2010) and 1)
SELECT * FROM t1 WHERE a=2010 AND CASE WHEN 10.1=a THEN NULL ELSE 10.1 END IS NULL;
a
2010
EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=2010 AND CASE WHEN 10.1=a THEN NULL ELSE 10.1 END IS NULL;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 2 100.00 Using where
Warnings:
Note 1003 select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((`test`.`t1`.`a` = 2010) and 1)
DROP TABLE t1;
# Two warnings expected
CREATE TABLE t1 AS SELECT
NULLIF(TIMESTAMP'2001-01-01 00:00:00',1) AS a,
CASE WHEN TIMESTAMP'2001-01-01 00:00:00'=1 THEN NULL
ELSE TIMESTAMP'2001-01-01 00:00:00'
END AS b;
Warnings:
Warning 1292 Incorrect datetime value: '1'
Warning 1292 Incorrect datetime value: '1'
DROP TABLE t1;
#
# End of 10.1 tests
#

20
mysql-test/t/null.test
View file

@ -849,6 +849,26 @@ DROP TABLE t2;
DROP TABLE t1;
--echo #
--echo # MDEV-7759 NULLIF(x,y) is not equal to CASE WHEN x=y THEN NULL ELSE x END
--echo #
CREATE TABLE t1 (a YEAR);
INSERT INTO t1 VALUES (2010),(2020);
SELECT * FROM t1 WHERE a=2010 AND NULLIF(10.1,a) IS NULL;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=2010 AND NULLIF(10.1,a) IS NULL;
SELECT * FROM t1 WHERE a=2010 AND CASE WHEN 10.1=a THEN NULL ELSE 10.1 END IS NULL;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=2010 AND CASE WHEN 10.1=a THEN NULL ELSE 10.1 END IS NULL;
DROP TABLE t1;
--echo # Two warnings expected
CREATE TABLE t1 AS SELECT
NULLIF(TIMESTAMP'2001-01-01 00:00:00',1) AS a,
CASE WHEN TIMESTAMP'2001-01-01 00:00:00'=1 THEN NULL
ELSE TIMESTAMP'2001-01-01 00:00:00'
END AS b;
DROP TABLE t1;
--echo #
--echo # End of 10.1 tests
--echo #

53
sql/item_cmpfunc.cc
View file

@ -552,6 +552,26 @@ void Item_func::convert_const_compared_to_int_field(THD *thd)
}
bool Item_func::setup_args_and_comparator(THD *thd, Arg_comparator *cmp)
{
DBUG_ASSERT(arg_count == 2);
if (args[0]->cmp_type() == STRING_RESULT &&
args[1]->cmp_type() == STRING_RESULT &&
agg_arg_charsets_for_comparison(cmp->cmp_collation, args, 2))
return true;
args[0]->cmp_context= args[1]->cmp_context=
item_cmp_type(args[0]->result_type(), args[1]->result_type());
// Convert constants when compared to int/year field, unless this is LIKE
if (functype() != LIKE_FUNC)
convert_const_compared_to_int_field(thd);
return cmp->set_cmp_func(this, tmp_arg, tmp_arg + 1, true);
}
void Item_bool_func2::fix_length_and_dec()
{
max_length= 1; // Function returns 0 or 1
@ -562,32 +582,7 @@ void Item_bool_func2::fix_length_and_dec()
*/
if (!args[0] || !args[1])
return;
/*
We allow to convert to Unicode character sets in some cases.
The conditions when conversion is possible are:
- arguments A and B have different charsets
- A wins according to coercibility rules
- character set of A is superset for character set of B
If all of the above is true, then it's possible to convert
B into the character set of A, and then compare according
to the collation of A.
*/
DTCollation coll;
if (args[0]->cmp_type() == STRING_RESULT &&
args[1]->cmp_type() == STRING_RESULT &&
agg_arg_charsets_for_comparison(coll, args, 2))
return;
args[0]->cmp_context= args[1]->cmp_context=
item_cmp_type(args[0]->result_type(), args[1]->result_type());
// Convert constants when compared to int/year field, unless this is LIKE
if (functype() != LIKE_FUNC)
convert_const_compared_to_int_field(current_thd);
set_cmp_func();
setup_args_and_comparator(current_thd, &cmp);
}
@ -2760,12 +2755,8 @@ Item_func_nullif::fix_length_and_dec()
decimals= m_args0_copy->decimals;
unsigned_flag= m_args0_copy->unsigned_flag;
fix_char_length(m_args0_copy->max_char_length());
convert_const_compared_to_int_field(current_thd);
m_args0_copy->cmp_context= args[1]->cmp_context=
item_cmp_type(m_args0_copy->result_type(), args[1]->result_type());
cmp.set_cmp_func(this, tmp_arg, tmp_arg + 1, m_args0_copy->cmp_context);
maybe_null=1;
setup_args_and_comparator(current_thd, &cmp);
}

3
sql/item_cmpfunc.h
View file

@ -66,10 +66,11 @@ public:
Arg_comparator(Item **a1, Item **a2): a(a1), b(a2), set_null(TRUE),
comparators(0), thd(0), a_cache(0), b_cache(0) {};
private:
int set_cmp_func(Item_result_field *owner_arg,
Item **a1, Item **a2,
Item_result type);
public:
inline int set_cmp_func(Item_result_field *owner_arg,
Item **a1, Item **a2, bool set_null_arg)
{

9
sql/item_func.h
View file

@ -398,6 +398,15 @@ public:
walk(&Item::call_bool_func_processor, FALSE, (uchar*) &info);
}
void convert_const_compared_to_int_field(THD *thd);
/**
Prepare arguments and setup a comparator.
Used in Item_func_xxx with two arguments and a comparator,
e.g. Item_bool_func2 and Item_func_nullif.
args[0] or args[1] can be modified:
- converted to character set and collation of the operation
- or replaced to an Item_int_with_ref
*/
bool setup_args_and_comparator(THD *thd, Arg_comparator *cmp);
};