mysql如何根據各自條件批量更新

問題描述

現有兩張表，A是明細表id uid cost

0

1

4

3

現在要把把該表中cost大于0的數據，根據uid分組然后更新到另一個表上

select uid,count(cost) as count from A group by uid where cost > 0

這是取出的語句，有沒辦法一句話把這個查詢結果根據uid更新到另一張表上？

問題解答

update B b set b.col=(select count(a.cost) as count from A a where cost > 0 and a.uid=b.uid group by uid)