求一个SQL语句

[hexinyu2005]

有一个表 A
aid bid cid sumvalue
1 2 3 0
2 2 3 0
3 2 3 0

还有一个表B
aid bid cid sumvalue

2 2 3 88


现在想把B的数据插入到A中去,要求aid,bid,cid都是对得上的,结果就是

有一个表 A
aid bid cid sumvalue
1 2 3 0
2 2 3 88
3 2 3 0

[fcuandy]

update a set sumvalue=b.sumvalue
from a inner join b on a.aid=b.aid and a.bid=b.bid and a.cid=b.cid
不排除手误

[xyxfly]

update a set sumvalue=b.sumvalue
from a,b where a.aid=b.aid and a.bid=b.bid and a.cid=b.cid

[mugua604]

update a set sumvalue=b.sumvalue
from a,b on a.aid=b.aid and a.bid=b.bid and a.cid=b.cid