MySQL的内部联接 [英] mysql INNER JOIN

问题描述

我正在使用以下查询从数据库的不同表中获取报告，请检查以下内容...

I am using following query to get report from different table of my database, check following...

SELECT s.id, s.name, c.name AS course_name,
s.open_bal AS open_balance, sum(i.amount) AS gross_fee,
sum(i.discount) AS discount, sum(i.amount) - sum(i.discount) AS net_payable,
SUM(r.reg_fee+r.tut_fee+r.other_fee) AS net_recieved,
(sum(i.amount) - sum(i.discount)) - SUM(r.reg_fee+r.tut_fee+r.other_fee) AS balance_due
FROM students s
INNER JOIN courses c on c.id = s.course_id
LEFT JOIN invoices i on i.student_id = s.id
LEFT JOIN recipts r on r.student_id = s.id;

发票

| id | student_id | amount   | discount |  dnt        | 
+----+------------+----------+----------+-------------+
| 2  | 22         | 35000    | 0        |  2011/01/01 |
+----+------------+----------+----------+-------------+

未从Gross_fee和net_payable中获得正确的值.

Not getting correct value from gross_fee and net_payable.

谢谢.

推荐答案

鉴于select中的SUM，我想GROUP BY s.id应该可以解决问题.无论如何，GROUP BY似乎丢失了:)

Given the SUMs in the select I suppose that GROUP BY s.id should do the trick. Anyway a GROUP BY seems to be missing :)

SELECT s.id, s.name, c.name AS course_name,
s.open_bal AS open_balance,
SUM(r.reg_fee+r.tut_fee+r.other_fee) AS net_recieved,
 (sum(i.amount) - sum(i.discount)) - SUM(r.reg_fee+r.tut_fee+r.other_fee) AS balance_due
FROM students s
INNER JOIN courses c on c.id = s.course_id
LEFT JOIN invoices i on i.student_id = s.id
LEFT JOIN recipts r on r.student_id = s.id
GROUP BY s.id;

编辑

单独的查询，允许检索所有发票的 gross_fee 和 net_payable

Separate query allowing to retrieve gross_fee and net_payable for all invoices

SELECT sum(amount) AS gross_fee,
  sum(discount) AS discount,
  sum(amount) - sum(discount) AS net_payable,
FROM invoices;

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