[英]MySql Join more than 2 tables?
使用MySql示例连接两个以上的表:
SELECT i.*
FROM ownedskins o
JOIN inventory i
ON o.inventory_id=i.inventory_id
JOIN user u
ON u.user_id = i.user_id
WHERE u.user_id = 1
使用联接非常容易,请使用以下方法:
SELECT *
FROM table1 t1
JOIN table2 t2 ON t1.id = t2.id
JOIN table3 t3 ON t2.id2 = t3.id
您还可以使用JOIN变体,例如LEFT JOIN,INNER JOIN,OUTER JOIN ...
假设您有以下表格:
Driver
Car
Keys
如果您想访问全部三个,则可以执行以下操作:
SELECT D.name, C.plate, K.state
FROM Driver D, Car C, Keys K
WHERE C.key_id = K.id and
K.owner_id = D.id;
使用JOINS:
SELECT D.name, C.plate, K.state
FROM Car C JOIN Keys K
ON C.key_id = K.id JOIN Driver D
ON K.owner_id = D.id;
假设您知道user_id
,则可以通过单个join
来做到这一点,如下所示:
SELECT
ownedskins.*
FROM
ownedskins JOIN inventory ON ownedskins.inventory_id = inventory.inventory_id
WHERE
inventory.user_id = x
其中x
是您想要的用户的ID
您也可以使用别名使其看起来更整洁:
SELECT
os.*
FROM
ownedskins os JOIN inventory i ON os.inventory_id = i.inventory_id
WHERE
i.user_id = x
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.