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Fix for BUG#6976:

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In Item_ref::Item_ref set maybe_null (and other fields fix_fields sets) to be the 
same as in (*ref), because Item_ref::fix_fields() will not be called.  Previously 
maybe_null was 0 always and this produced a bogus state where 
maybe_null==0 && is_null() == true 
which broke evaluation for some upper-level Items, like AND and OR.
This commit is contained in:
sergefp@mysql.com
2004-12-11 19:59:09 +03:00
parent 13649d90ae
commit f78a60593a
4 changed files with 35 additions and 1 deletions
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12
mysql-test/r/group_by.result
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@@ -626,3 +626,15 @@ explain SELECT i, COUNT(DISTINCT(i)) FROM t1 GROUP BY j ORDER BY NULL;
table type possible_keys key key_len ref rows Extra
t1 ALL NULL NULL NULL NULL 6 Using filesort
DROP TABLE t1;
create table t1 (a int);
insert into t1 values(null);
select min(a) is null from t1;
min(a) is null
1
select min(a) is null or null from t1;
min(a) is null or null
1
select 1 and min(a) is null from t1;
1 and min(a) is null
1
drop table t1;

9
mysql-test/t/group_by.test
View File

@@ -447,3 +447,12 @@ INSERT INTO t1 VALUES (1,2),(2,3),(4,5),(3,5),(1,5),(23,5);
SELECT i, COUNT(DISTINCT(i)) FROM t1 GROUP BY j ORDER BY NULL;
explain SELECT i, COUNT(DISTINCT(i)) FROM t1 GROUP BY j ORDER BY NULL;
DROP TABLE t1;
#Test for BUG#6976: Aggregate functions have incorrect NULL-ness
create table t1 (a int);
insert into t1 values(null);
select min(a) is null from t1;
select min(a) is null or null from t1;
select 1 and min(a) is null from t1;
drop table t1;