请教一个mysql查询问题，送上100分
本帖最后由 SHANDIANDIAN 于 2013-12-12 12:15:27 编辑 表A 表B
uid mid cash uid mid cash number
1 1 100 1 1 101 100
2 2 105 2 1 100 100
3 3 98 3 2 105 200
4 4 55 4 2 105 300
5 5 60 5 3 60 300
6 6 70 6 3 98 300
uid 是自动增长字段 mid和cash 是关联字段
我想统计出 表B的求和数量就和下面这样，没匹配到表A就显示0，匹配通过mid和cash 两字段。请问SQL该怎么写？？ 以表A为基础表
结果表
uid mid cash number
1 1 100 100
2 2 105 500
3 3 98 300
4 4 55 0
5 5 60 0
6 6 70 0
[解决办法]
你太调皮，后来编辑过帖子了
看这个
http://sqlfiddle.com/#!2/9847b/12
[解决办法]
create temporary table A1 1 100 100
select 1 as uid, 1 as mid, 100 as cash
union select 2, 2, 105
union select 3, 3, 98
union select 4, 4, 55
union select 5, 5, 60
union select 6, 6, 70;
create temporary table B
select 1 as uid, 1 as mid, 101 as cash, 100 as number
union select 2, 1, 100, 100
union select 3, 2, 105, 200
union select 4, 2, 105, 300
union select 5, 3, 60, 300
union select 6, 3, 98, 300;
select uid,mid, cash, (select sum(number) from B where mid=A.mid and cash=A.cash) from A
select a.uid, a.mid, a.cash, sum(b.number) from testa as a left join testb as b on a.mid=b.mid and a.cash = b.cash group by a.mid, a.cash
