mysql - 在同一查询中从借方列减去贷方？

Question

我有以下查询:

SELECT user_id, SUM( credit ) 作为 cred, SUM( debit ) 作为 deb 从帐户 WHERE user_id = '35'

我想从贷方中减去借方并将其显示在一列中或作为变量中的值

Answer 1

这应该可以工作，并且可能比其他两个 SUM 快一点

SELECT a.user_id, 
       a.cred, 
       a.deb, 
       a.deb - a.cred AS value 
FROM   (SELECT user_id, 
               Sum(credit) AS cred, 
               Sum(debit)  AS deb 
        FROM   account 
        WHERE  user_id = '35') a 

如果你有多个用户，你可以这样做:

SELECT a.user_id, 
       a.cred, 
       a.deb, 
       a.deb - a.cred AS value 
FROM   (SELECT user_id, 
               Sum(credit) AS cred, 
               Sum(debit)  AS deb 
        FROM   account 
        WHERE  user_id IN (35, 36, 39)
        GROUP BY user_id) a 

See the demo