两个mysql表列的总和

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：loan中获取“loan\u amount”的和，从表：advance中获取“advance\u amount”的和，在一个由内部联接连接的mysql查询中

如何从两个表的列中求和

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 

---

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 

---

选择a.advance\u id，sum（a.advance\u amount）作为adv\u amount，a.purpose，a.date，sum（l.loan\u amount），sum（l.loan\u amount），sum（l.loan\u amount），sum（l.loan\u amount），sum（l.loan\u amount）作为内部联接贷款作为l ON a.advance\u id=l.advance\u id组，由a.advance\u id组成，sum（a.advance\u amount