请教Oracle中,一条Sql语句问题.在线等,急用,谢谢.

[jash_dou]

表A 字段 a,b,c.a,b为主键,c为记载时间的字符串
表B 字段 a,b,c.c为记载时间的字符串
其中表A和表B 是一对多关系.

现在要实现的是:把表A中的c字段,修改为表B中符合(A.a = B.a and A.b = B.b)
条件的最大的c字段的值.
update (select max(b.c) as bc,A.c as ac,A.a from A,B
where A.a = B.a and A.b = B.b group by ac,A.a ) set bc = ac
实现不了,哪位大虾给帮帮忙,谢谢.

[updatename]

~up

[jash_dou]

没有人守望相助吗?

[dashi]

友情up

[Paladin_china]

update A t1 set
c = (select max(t2.c) from B t2 where t2.a = t1.a and t2.b = t1.b )
where exists (select 'X' from B t3 where t3.a = t1.a and t3.b = t1.b)

[Paladin_china]

大致这样，没有调试过，如果不行的话自己再修改一下吧 :)

[gqcwin]

uP

[eeyyllehs]

帮顶

[haosimentu]

update A set A.c=( select max(B.c) from A,B where A.a = B.a and A.b = B.b)
where A.a=(select A.a from A,B where A.a = B.a and A.b = B.b)

[DragonBill]

update A set c = (select max(c) from B where A.a = B.a and A.b = B.b)
where exists (select 1 from B where A.a = B.a and A.b = B.b)