关于MySQL多表联查并求和计算？

Question

是这样的一个情况 这里有三张表 分别是用户user，订单 trade ，和资金记录 user_money_record现在要根据用户来统计他们的订单总金额和账户余额以及充值总金额 user表id realname money1 张xx 1002 王xx 5003 李xx...

怪我咯 · Answer

我猜想你可能是要这样的

select u.name,t.realmoney,umr.money from user u
left join 
(select uid,sum(realmoney) as realmoney from trade group by uid) t on t.uid = u.id
left join
(select uid,sum(money) as money from user_money_record group by uid) umr on umr.uid = uid

天蓬老师 · Answer

如果user表的信息是最完整的，应该是这样的：

SELECT *
FROM (SELECT id, sum(money) FROM user GROUP BY id) t1 
  LEFT JOIN (SELECT id, sum(realmoney) FROM trade GROUP BY id) t2 ON t1.id = t2.id
  LEFT JOIN (SELECT id, sum(money) FROM user_money_record GROUP BY id) t3 ON t1.id = t3.id

ringa_lee · Answer

对于这样的情况假如数据量过大的情况如何处理