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Fix for MIN/MAX with empty tables

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MIN(key_column) could in some cases return NULL on a column with NULL and other values.
MIN(key_column) and MAX(key_column) could in some cases return wrong values when used in OUTER JOIN.
This commit is contained in:
monty@mashka.mysql.fi
2003-02-03 20:20:32 +02:00
parent c42e94a6e6
commit e3cd63521c
8 changed files with 158 additions and 27 deletions
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53
mysql-test/r/func_group.result
View File

@ -151,3 +151,56 @@ sum(num)
45.63
51.80
drop table t1;
create table t1 (a1 int, a2 char(3), key k1(a1), key k2(a2));
insert into t1 values(10,'aaa'), (10,null), (10,'bbb'), (20,'zzz');
create table t2(a1 char(3), a2 int, a3 real, key k1(a1), key k2(a2, a1));
select * from t1;
a1 a2
10 aaa
10 NULL
10 bbb
20 zzz
select min(a2) from t1;
min(a2)
aaa
select max(t1.a1), max(t2.a2) from t1, t2;
max(t1.a1) max(t2.a2)
NULL NULL
select max(t1.a1) from t1, t2;
max(t1.a1)
NULL
select max(t2.a2), max(t1.a1) from t1, t2;
max(t2.a2) max(t1.a1)
NULL NULL
explain select min(a2) from t1;
Comment
Select tables optimized away
explain select max(t1.a1), max(t2.a2) from t1, t2;
Comment
No matching min/max row
insert into t2 values('AAA', 10, 0.5);
select max(t1.a1), max(t2.a1) from t1, t2 where t2.a2=9;
max(t1.a1) max(t2.a1)
NULL NULL
select max(t2.a1), max(t1.a1) from t1, t2 where t2.a2=9;
max(t2.a1) max(t1.a1)
NULL NULL
select t1.a1, t1.a2, t2.a1, t2.a2 from t1 left outer join t2 on t1.a1=10;
a1 a2 a1 a2
10 aaa AAA 10
10 NULL AAA 10
10 bbb AAA 10
20 zzz NULL NULL
select max(t1.a2) from t1 left outer join t2 on t1.a1=10;
max(t1.a2)
zzz
select max(t1.a2) from t1 left outer join t2 on t1.a1=10 where t1.a1=20;
max(t1.a2)
zzz
select max(t1.a2) from t1 left outer join t2 on t1.a1=10 where t1.a1=10;
max(t1.a2)
bbb
select max(t2.a1) from t1 left outer join t2 on t1.a2=t2.a1 and 1=0 where t2.a1='AAA';
max(t2.a1)
NULL
drop table t1,t2;

27
mysql-test/t/func_group.test
View File

@ -99,3 +99,30 @@ insert into t1 values (5.2,'nem'),(8.64,'monty'),(11.12,'sinisa');
select sum(num) from t1;
select sum(num) from t1 group by user;
drop table t1;
#
# Test problem with MIN() optimization in case of null values
#
create table t1 (a1 int, a2 char(3), key k1(a1), key k2(a2));
insert into t1 values(10,'aaa'), (10,null), (10,'bbb'), (20,'zzz');
create table t2(a1 char(3), a2 int, a3 real, key k1(a1), key k2(a2, a1));
select * from t1;
# The following returned NULL in 4.0.10
select min(a2) from t1;
select max(t1.a1), max(t2.a2) from t1, t2;
select max(t1.a1) from t1, t2;
select max(t2.a2), max(t1.a1) from t1, t2;
explain select min(a2) from t1;
explain select max(t1.a1), max(t2.a2) from t1, t2;
insert into t2 values('AAA', 10, 0.5);
select max(t1.a1), max(t2.a1) from t1, t2 where t2.a2=9;
select max(t2.a1), max(t1.a1) from t1, t2 where t2.a2=9;
select t1.a1, t1.a2, t2.a1, t2.a2 from t1 left outer join t2 on t1.a1=10;
select max(t1.a2) from t1 left outer join t2 on t1.a1=10;
select max(t1.a2) from t1 left outer join t2 on t1.a1=10 where t1.a1=20;
select max(t1.a2) from t1 left outer join t2 on t1.a1=10 where t1.a1=10;
select max(t2.a1) from t1 left outer join t2 on t1.a2=t2.a1 and 1=0 where t2.a1='AAA';
drop table t1,t2;