加入子查询

Question

我有4张桌子

1. members(id, name, milk_no, ...)
2. collections(id, member_id, amount, date, ...)
3. credit_payment_transaction(id, member_id, amount, date, ...)
4. deductions(id, member_id, amount, date, ...)

我想提出一个查询，每个成员 return。

milk_no | totalDeduction  | totalStore | totalCollection

结果应该 return 唯一具有至少 totalDeduction | totalStore | totalCollection

之一的成员

这是我想出来的

SELECT members.milk_no, memberCollections.totalCollection, stores.totalStore, memberDeductions.totalDeduction
FROM members
LEFT JOIN 
   (SELECT SUM(amount) AS totalCollection, member_id 
    FROM collections 
    GROUP BY member_id) AS memberCollections
    ON memberCollections.member_id = members.id
    
LEFT JOIN 
   (SELECT SUM(amount) AS totalStore, member_id 
    FROM credit_payment_transaction 
    GROUP BY member_id) AS stores
    ON stores.member_id = members.id        
    
LEFT JOIN 
   (SELECT SUM(amount) AS totalDeduction, member_id 
    FROM deductions 
    GROUP BY member_id) AS memberDeductions
    ON memberDeductions.member_id = members.id

上面的查询return这个

此结果的问题在于，它包含不需要的数据（具有 3 个空值的数据）。当我更改为 RIGHT JOIN 时，根本 return 没有结果。

Answer 1

只需在查询底部添加一个 WHERE 子句：

WHERE totalCollection IS NOT NULL OR totalStore IS NOT NULL OR totalDeduction IS NOT NULL

您可以像这样简化您的查询：

SELECT m.id, SUM(c.amount) AS totalCollection, SUM(cpt.amount) AS totalStore, SUM(d.amount) AS totalDeduction
FROM members m
LEFT JOIN collections c ON m.id = c.member_id
LEFT JOIN credit_payment_transaction cpt ON m.id = cpt.member_id
LEFT JOIN deductions d ON m.id = d.member_id
GROUP BY m.id
HAVING SUM(c.amount) > 0 OR  SUM(cpt.amount) > 0 OR SUM(d.amount) > 0

此查询还将消除成员重复

加入子查询

Join with subquery

java

mysql

sql

join

subquery