Question

嘿伙计们，我有一个允许我对大型数据库运行查询的程序。我现在有两张桌子很重要，存款和取款。每个都包含每个用户的历史记录。我需要拿每张桌子，将每笔存款加起来（每位用户），然后从存款中扣除。然后我需要返回每个结果为负的用户（也就是说他们退出了更多然后存入）。这可能在一个查询中吗？
示例：

Deposit Table:

|ID|UserName|Amount|
|1 |  Use1  |100.00|
|2 |  Use1  |50.00 |
|3 |  Use2  |25.00 |
|4 |  Use1  | 5.00 |

WithDraw Table:
|ID|UserName|Amount|
|2 |  Use2  | 5.00 |
|1 |  Use1  |100.00|
|4 |  Use1  | 5.00 |
|3 |  Use2  |25.00 |

So then the result would output:
|OverWithdrawers|
|      Use2     |

这可能吗（我肯定不知道怎么做）？谢谢你的帮助，最大

Answer 1

试试这个：

SELECT T1.UserName
FROM
(
    SELECT UserName, SUM(Amount) AS Amount
    FROM WithDraw
    GROUP BY UserName
) T1
LEFT JOIN
(
    SELECT UserName, SUM(Amount) AS Amount
    FROM Deposit
    GROUP BY UserName
) T2
ON T1.UserName = T2.UserName
WHERE T1.Amount > COALESCE(T2.Amount, 0)

COALESCE如果有用户退出但从未存放过，也可以使用。

Answer 2

另一种方法：

SELECT UserName, SUM(Amount) AS Amount
FROM (
    SELECT UserName, Amount
    FROM Deposit
    UNION ALL
    SELECT UserName, -Amount
    FROM WithDraw
) AS U (UserName, Amount)
GROUP BY UserName
HAVING SUM(Amount) < 0

Answer 3

更正了工作版本：

Select innersql.UserName from (
    select 
          d.username,
          SUM(d.Amount) as depositamount,
          SUM(w.WithDraw)as withdrawamount 
    from deposit d
    inner join withdraw w
    on d.UserName = w.UserName
    group by d.UserName
     ) as innersql where depositamount > withdrawamount

在SQL中查找透支帐户

3 个答案: