Question

这是一般的SQL问题

我有这个表（简化），积分是积极的，借记是负面的：

Account Amount  Type
--------------------
john    25      credit  
john    45      debit  
john    5       debit  
john    15      credit  
mike    15      credit

我想使用Case When使用单个查询得到这样的结果：

Account  Total
--------------------
john     -10      
mike     15

提前感谢任何建议。

Answer 1

您可以使用CASE构造来区分借记和贷记条目。

SELECT   account, SUM (amount * CASE type WHEN 'credit' THEN 1 ELSE -1 END)
FROM     my_table
GROUP BY account

Answer 2

如果对您更有意义，您还可以尝试以下方法：

SELECT a.Account, b.Credits - a.Debits AS Total FROM
    (SELECT Account, SUM(Amount) AS Debits
        FROM YourTable GROUP BY Account HAVING Type = 'debit'
    ) AS a
    INNER JOIN
    (SELECT Account, SUM(Amount) AS Credits
        FROM YourTable GROUP BY Account HAVING Type = 'credit'
    ) AS b

Answer 3

sum(amount * case when type = 'debit' then -1 else 1 end)

总和案例查询时

3 个答案: