即使第二个表上的行不存在,也要正确连接

Question

我想加入两个表,即使第二个表没有匹配.

表用户:

uid | name
1     dude1
2     dude2

表帐户:

uid | accountid | name
1     1           account1

我想要的表:

uid  | username | accountname
1      dude1      account1
2      dude2      NULL

我正在尝试的查询:

SELECT user.uid as uid, user.name as username, account.name as accountname
FROM user RIGHT JOIN account ON user.uid=accout.uid

我得到了什么:

uid  | username | accountname
1      dude1      account1

Answer 1

使用Left Join替代

SELECT user.uid as uid, user.name as username, account.name as accountname
FROM user LEFT JOIN account ON user.uid=accountid.uid

Answer 2

尝试LEFT JOIN查询

SELECT user.uid as uid, user.name as username, account.name as accountname
FROM user 
LEFT JOIN account 
ON user.uid=accout.uid

我想让你看看这个查询的可视化表示JOIN

Answer 3

右联接保留第二个表中的所有结果（它将所有结果保留在右侧表中），您想要左联接，或者在联接子句中交换用户和帐户的位置。

SELECT user.uid as uid, user.name as username, account.name as accountname
FROM user LEFT JOIN account ON user.uid=account.uid

我相信应该这样做。