三个表怎么做关联？
条件：
表A的number=表B的number=表C的number
表A的time=表C的time=20120312
表A的level=2
我现在是这样写的:
- SQL code
select 表C.Value from 表A,表B,表C where 表A.number=表B.number and 表B.number=表C.number and 表A.level = 2 and 表A.time=to_date('20120311','yyyy/mm/dd') and 表C.time=to_date('20120311','yyyy/mm/dd')[解决办法]
以表A为基础来关联
- SQL code
select C.Value from A,B,C where A.number=B.number and A.number=C.number and A.level = 2 and A.time=C.time and A.time=to_date('20120311','yyyy/mm/dd')
[解决办法]
- SQL code
select C.Value from A,B,C where A.number=B.number and A.number=C.number and A.level = 2 and A.time=C.time and to_char(A.time,'yyyy/mm/dd')='20120311'