SQL SERVER 内连接和嵌套,哪个效率更高?
风车呼噜噜 2011-11-15 11:20:58 我现在有两个表 A(数据量很大),B(数据量相对较小),现在我进行关联查询
1. select A.* from A inner join B on(A.field1=B.field1 and B.field2=var)
2. select A.* from A inner join (select * from B where b.field2=var) tt on(tt.field1=A.field1)
3. select * from A where a.field1 in(select b.field1 form B where field2=var)
请高手指点那种效率更高,最好有实际用过的说说心得,谢谢!