5
5
drop table if exists t1,t2;
8
create table t1 (a int, b int not null,unique key (a,b),index(b)) engine=myisam;
8
create temporary table t1 (a int, b int not null,unique key (a,b),index(b)) engine=myisam;
9
9
insert ignore into t1 values (1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(null,7),(9,9),(8,8),(7,7),(null,9),(null,9),(6,6);
10
10
explain select * from t1 where a is null;
11
11
explain select * from t1 where a is null and b = 2;