SQL优化-关联子查询改表连接

1.数据脚本

drop table test1 ;

create table test1 as

  select * from (select d.*,rownum as rn

                 from dba_objects d

                             where d.owner not in ('SYS','SYSTEM','PUBLIC'))

              where mod(rn,20)=0;

alter table test1 add constraint pk_test1 primary key (object_id);

2.SQL优化

2.1 优化前

select t1.*

from test1 t1

where t1.object_id in (select t2.object_id

                       from test2 t2