php - MySQL JOIN 查询在不同数据库上给出不同结果

Question

我正在对计算机上本地安装的数据库运行查询，得到的结果与在 AWS RDS 数据库上运行时得到的结果不同。我正在运行:

SELECT SUM(Hours) AS 'TotalHours', Username, Name, Project_Name, Project_Ref, (37.5-SUM(Hours)) AS 'Missing'  
FROM bookings b 
JOIN projects p ON b.Project_ID=p.Project_ID 
RIGHT JOIN users u ON b.User_ID=u.User_ID   
WHERE  ((Date BETWEEN '2017-07-01' AND '2017-07-30') OR Date IS NULL) 
GROUP BY u.User_ID

当在本地运行时，我会取回用户表中的每个条目，即使他们没有在预订表上进行预订。

当在我的服务器数据库上运行时，我只返回已预订的用户，而不会像执行正确连接时预期的那样输入。

Answer 1

尝试使用LEFT JOIN而不是RIGHT JOIN，并将Date条件放入ON子句中:

SELECT SUM(Hours) AS 'TotalHours', Username, Name, Project_Name, Project_Ref, (37.5-SUM(Hours)) AS 'Missing'  
FROM users AS u
LEFT JOIN bookings AS b ON b.User_ID = u.User_ID AND b.DATE BETWEEN '2017-07-01' AND '2017-07-30'
LEFT JOIN projects AS p ON b.Project_ID=p.Project_ID

我怀疑问题与 users 和 bookings 表之间的 projects 的 INNER JOIN 有关.