Question

我试图在WHERE子句中进行简单的减法工作，我有以下内容：

SELECT account, SUM(payments) AS total_payments, amount_due FROM clients
LEFT JOIN payments ON clients.id = payments.id
LEFT JOIN account_details ON clients.id = account_details.id
WHERE account_details.amount_due - SUM(payments) < 0

我做错了什么？

Answer 1

您不能在where子句中使用SUM。试试这个：

SELECT account, SUM(payments) AS total_payments, amount_due FROM clients
LEFT JOIN payments ON clients.id = payments.id
LEFT JOIN account_details ON clients.id = account_details.id
GROUP BY account
HAVING SUM(payments) < 0;

Answer 2

你可以这样做，但无论如何它不是最佳查询。

SELECT a.* from 

 (SELECT account, SUM(payments) AS total_payments, amount_due FROM clients 
 LEFT JOIN payments ON clients.id = payments.id)as a

LEFT JOIN account_details ON clients.id = account_details.id
WHERE account_details.amount_due - a.total_payments < 0

MYSQL在WHERE子句中减去

2 个答案: