这个SQL怎么可能是错误的?我没看到什么? [英] How can this SQL be wrong? What am I not seeing?

问题描述

有人可以发现我的错误吗，这应该是SQL中的合法查询吗?

ON子句中的未知列u.usr_auto_key

Unknown column u.usr_auto_key in the ON clause

这是数据库架构:

User: (usr_auto_key, name, etc...)
Setting: (set_auto_key, name etc..)
User_Setting: (usr_auto_key, set_auto_key, value)

这是查询...

        SELECT 
        `u`.`usr_auto_key` AS `u__usr_auto_key`, 
        `s`.`set_auto_key` AS `s__set_auto_key`, 
        `u2`.`usr_auto_key` AS `u2__usr_auto_key`, 
        `u2`.`set_auto_key` AS `u2__set_auto_key`, 
        `u2`.`value` AS `u2__value` 
        FROM `User` `u`, `Setting` `s` 
        LEFT JOIN `User_Setting` `u2` ON `u`.`usr_auto_key` = `u2`.`usr_auto_key` 
        WHERE (`s`.`sct_auto_key` = 1 AND `u`.`usr_auto_key` = 1 AND admin_property is null)

推荐答案

尝试在from子句中切换User和Settings:

Try switching User and Settings in the from clause:

SELECT 
        `u`.`usr_auto_key` AS `u__usr_auto_key`, 
        `s`.`set_auto_key` AS `s__set_auto_key`, 
        `u2`.`usr_auto_key` AS `u2__usr_auto_key`, 
        `u2`.`set_auto_key` AS `u2__set_auto_key`, 
        `u2`.`value` AS `u2__value` 
        FROM `Setting` `s`, `Users` `u`
        LEFT JOIN `User_Setting` `u2` ON `u`.`usr_auto_key` = `u2`.`usr_auto_key` 
        WHERE (`s`.`sct_auto_key` = 1 AND `u`.`usr_auto_key` = 1 AND admin_property is null)

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