Oracle查询两表相差的数据

原来以为not exists 会比not in 效率高,但在实际运用过程中,发现两表数据差不多的情况下,用另一种方式效率会更好.

原设计语句:

select * from (select * from ex_22222 where exattribute1 = '13') K1 where not exists

(

select * from

(

select ex_22222.entityid from ex_22222,ut_users where exattribute1 = '13'

and ex_22222.entityid = ut_users."UID"

) K2

where K1.ENTITYID = K2.ENTITYID

)

新改进语句:

select K1.ENTITYID,K2.ENTITYID from (select * from ex_22222  where exattribute1 = '13') K1,

(

select * from

(

select ex_22222.entityid from ex_22222,ut_users where exattribute1 = '13'

and ex_22222.entityid = ut_users."UID"

)

) K2

where K1.ENTITYID = K2.ENTITYID(+)

and K2.ENTITYID is null