来自同一查询的借记栏的减去信用额度？

Question

我有以下查询：

SELECT user_id，SUM（credit）AS cred，SUM（debit）AS deb FROM account WHERE user_id ='35'

我希望减去信用卡的借记并将其显示在一列中或作为变量中的值显示

Answer 1

这应该工作，并且可能比执行其他两个SUM略快

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 

如果您有多个用户，则可以执行以下操作：

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 

看演示

Answer 2

你可以计算同一行的差异

SELECT  user_id, 
        SUM(credit) AS cred, 
        SUM(debit) AS deb,
        SUM(credit) -  SUM(debit) total
FROM account 
WHERE user_id = 35

更新1

SELECT  user_id, 
        SUM(credit) AS cred, 
        SUM(debit) AS deb,
        SUM(credit) -  SUM(debit) total
FROM account 
WHERE user_id IN (30,31,32,33,34,35)
GROUP BY user_ID

更新2

SELECT  user_id, 
        SUM(credit) AS cred, 
        SUM(debit) AS deb,
        SUM(credit) -  SUM(debit) total
FROM account 
WHERE user_id IN (30,31,32,33,34,35)
GROUP BY user_ID
HAVING (SUM(credit) -  SUM(debit)) < 10