来自两个 mysql 表列的总和答案

【问题标题】：sum from both mysql table columns来自两个 mysql 表列的总和
【发布时间】：2015-06-25 22:14:05
【问题描述】：

我有两个mysql表：

table: loan
--------------------------------------------------------
 id | advance_id | loan_amount | deposit_amount | date
--------------------------------------------------------
 1 | 22556678 | 5000 | 0 | 2015-02-06
 2 | 22556678 | 5000 | 0 | 2015-02-07
--------------------------------------------------------

table: advance
--------------------------------------------------------
id | advance_id | advance_amount | purpose | date
--------------------------------------------------------
 1 | 22556678 | 20000 | purchase | 2015-01-30
 2 | 22556678 | 10000 | purchase | 2015-01-31

我想从表中获取“loan_amount”的总和：从表中获取贷款和“advance_amount”的总和：在一个由 INNER JOIN 连接的 mysql 查询中前进。

如何从两个表的列中得到总和？

SELECT 
  a.advance_id,
  SUM(a.advance_amount) AS adv_amount,
  a.purpose,
  a.date,
  SUM(l.loan_amount) AS loan_amount 
FROM
  advance AS a 
  INNER JOIN loan AS l 
    ON a.advance_id = l.advance_id 
GROUP BY a.advance_id 
HAVING SUM(l.loan_amount) - SUM(l.deposit_amount) > 0

【问题讨论】：

SELECT a.advance_id, sum(a.advance_amount) as adv_amount, a. purpose, a.date, sum(l.loan_amount) as loan_amount FROM Advance 作为 INNER JOIN 贷款作为 l ON a。 Advance_id=l.advance_id GROUP BY a.advance_id HAVING sum(l.loan_amount)-sum(l.deposit_amount)>0
但它使loan_amount 加倍

标签： mysql join sum

【解决方案1】：

您可以将查询重写为

SELECT 
  a.advance_id,
  SUM(a.advance_amount) AS adv_amount,
  a.purpose,
  a.date,
  l.loan_amount 
FROM
  advance AS a 
  INNER JOIN 
  (
    SELECT advance_id,SUM(deposit_amount) AS loan_amount
    FROM loan
    GROUP BY advance_id
    HAVING SUM(loan_amount) - SUM(deposit_amount) > 0 
  )  AS l USING(advance_id)
GROUP BY a.advance_id

DEMO

【讨论】：