三表查询，包含count,sum，SQL该如何写？
请教各位大侠，我在开发中遇到个问题，有三个表，user（用户）表，order（订单）表，app（订单评价）表，现在的需求是要用一个SQL联合查询出某个用户发不过的订单总数，及订单总金额，以及该用户的订单评价总条数。SQL我是这样写的：
SELECT u.id,u.`name`,COUNT( DISTINCT a.id ),COUNT( DISTINCT o.id ),SUM(o.money) 
FROM `user` u
INNER JOIN (SELECT id,to_user_id FROM `app` GROUP BY id) a ON u.id = a.to_user_id
LEFT JOIN (SELECT id,use_id,money FROM `order` GROUP BY id) o ON u.id = o.use_id
WHERE u.id =7;

但是查询出来的SUM值不对，比如正确的应该是10000，但实际返回的结果里，这个值里重复计算了很多次，变成60000这样。

请问这样的需求，语句该怎么写？


------解决方案--------------------
select * from user a left join
(select user_id,sum(money) as ma from order group by user_id) b
on a.id=b.user_id
left join
(select to_user_id,count(*) as mc from app group by to_user_id) c
on a.id=b.to_user_id
------解决方案--------------------

SQL code

select id,namae,
    (select count(*) from `order` where user_id=u.id) as 订单总数,
    (select sum(money) from `order` where user_id=u.id) as 总金额,
    (select count(*) from `app` where user_id=u.id) as 总数
from user u
where id=7