mysql分组错误

下面是我正在使用的一个查询

SELECT 
  `names`, sum(cashin.amount) as amountin, 
  sum(cashout.amount) as amountout, 
  (sum(cashin.amount) - sum(cashout.amount)) as total 
FROM (`client`) 
INNER JOIN `cashin` ON `cashin`.`clientid`=`client`.`id` 
INNER JOIN `cashout` ON `cashout`.`clientid`=`client`.`id` 
WHERE (sum(cashin.amount) - sum(cashout.amount)) < 0 
GROUP BY `client`.`id`

问题是我得到了一个错误：

组函数的使用无效

将where子句中的函数替换为字段别名“total”，仍然会出现错误：

未知列总数

如何修复此查询？

使用HAVING而不是WHERE，并将GROUP BY NAME子句而不是GROUP BY id置于HAVING子句之前，如下所示：

SELECT 
  `names`, 
  sum(cashin.amount) as amountin, 
  sum(cashout.amount) as amountout, 
  (sum(cashin.amount) - sum(cashout.amount)) as total 
FROM client
INNER JOIN `cashin` ON `cashin`.`clientid`=`client`.`id` 
INNER JOIN `cashout` ON `cashout`.`clientid`=`client`.`id` 
GROUP BY names
HAVING (sum(cashin.amount) - sum(cashout.amount)) < 0 

试试这个：

SELECT 
  `names`, 
  sum(cashin.amount) as amountin, 
  sum(cashout.amount) as amountout, 
  (sum(cashin.amount) - sum(cashout.amount)) as total 
FROM client
INNER JOIN `cashin` ON `cashin`.`clientid`=`client`.`id` 
INNER JOIN `cashout` ON `cashout`.`clientid`=`client`.`id` 
GROUP BY names
HAVING total < 0

---

作为使用HAVING子句的替代方法，您可以将查询包装在SELECT语句中，然后将筛选器放置在WHERE子句中：

---

你给这个取了个别名

   (sum(cashin.amount) - sum(cashout.amount)) as total

那么为什么你不在这里使用它呢

  WHERE (sum(cashin.amount) - sum(cashout.amount)) < 0

只用

  FROM `client`

还有这个

  (sum(cashin.amount) - sum(cashout.amount)) as total  // line 4

换成

     WHERE total < 0

   (amountin - amountout) as total 

这对你有好处

  (sum(cashin.amount) - sum(cashout.amount)) as total  // line 4

   (amountin - amountout) as total