1 echo create table t1(f1 int, f2 int, f3 varchar(20),f4 date);
2 create table t1(f1 int, f2 int, f3 varchar(20),f4 date);
3 echo create index idx on t1(f3,f4,f2) hash;
4 create index idx on t1(f3,f4,f2) hash;
5 echo explain plan select * from t1 where f2 is null;
6 explain plan select * from t1 where f2 is null;
7 echo explain plan select * from t1 where f2 is not null;
8 explain plan select * from t1 where f2 is not null;
9 echo explain plan select * from t1 where f2 is null and f3 is not null;
10 explain plan select * from t1 where f2 is null and f3 is not null;
11 echo explain plan select * from t1 where f1 is null or f2 is not null or f3 is null or f4 is not null;
12 explain plan select * from t1 where f1 is null or f2 is not null or f3 is null or f4 is not null;
13 echo explain plan select * from t1 where f1 is null and f2 is not null and f3 is null and f4 is not null;
14 explain plan select * from t1 where f1 is null and f2 is not null and f3 is null and f4 is not null;