Mysql - ON子句中的未知列

Question

我遇到了一个简单查询的问题。那就是：

SELECT `T_COURS`.`COU_DATE`, 
`T_SESSIONS`.*, 
`T_FORMATIONS`.`FOR_TITRE`, `T_FORMATIONS`.`FOR_ID`, `T_FORMATIONS`.`FOR_TITRE`,  `T_FORMATIONS`.`FOR_CATEGORIE`, 
`T_FORMATIONS`.`FOR_DESCRIPTION`, `T_FORMATIONS`.`FOR_MIN_PART`, `T_FORMATIONS`.`FOR_MAX_PART`, `T_FORMATIONS`.`FOR_PRIX`, `T_FORMATIONS`.`FOR_LANGUE` 
FROM `T_FORMATIONS` 
INNER JOIN `T_COURS` ON `T_SESSIONS`.`SES_ID` = `T_COURS`.`COU_SES_ID` 
INNER JOIN `T_SESSIONS` ON `T_FORMATIONS`.`FOR_ID` = `T_SESSIONS`.`SES_FOR_ID` 
WHERE `T_SESSIONS`.`SES_ETAT` = 1 
ORDER BY `T_COURS`.`COU_DATE` ASC, `T_SESSIONS`.`SES_TITRE` ASC, `T_FORMATIONS`.`FOR_TITRE` ASC LIMIT 5 

当我尝试运行它，我得到这个消息：

#1054 - Unknown column 'T_SESSIONS.SES_ID' in 'on clause' 

我真的不明白为什么，因为一切都在我的数据库中是否存在？

我在网上寻找答案，但它没有帮助我（或者我不明白我读的答案）。

Answer 1

没有看到您的全表结构，我会开始交换您的订单JOIN，您在尝试在当前版本中使用它时加入T_SESSIONS。您目前有：

FROM `T_FORMATIONS` 
INNER JOIN `T_COURS` 
    ON `T_SESSIONS`.`SES_ID` = `T_COURS`.`COU_SES_ID` 
INNER JOIN `T_SESSIONS` 
    ON `T_FORMATIONS`.`FOR_ID` = `T_SESSIONS`.`SES_FOR_ID` 

将其更改为：

FROM `T_FORMATIONS` 
INNER JOIN `T_SESSIONS` 
    ON `T_FORMATIONS`.`FOR_ID` = `T_SESSIONS`.`SES_FOR_ID` 
INNER JOIN `T_COURS` 
    ON `T_SESSIONS`.`SES_ID` = `T_COURS`.`COU_SES_ID` 

制作完整的查询：

SELECT `T_COURS`.`COU_DATE`, 
    `T_SESSIONS`.*, 
    `T_FORMATIONS`.`FOR_TITRE`, 
    `T_FORMATIONS`.`FOR_ID`, 
    `T_FORMATIONS`.`FOR_TITRE`,  
    `T_FORMATIONS`.`FOR_CATEGORIE`, 
    `T_FORMATIONS`.`FOR_DESCRIPTION`, 
    `T_FORMATIONS`.`FOR_MIN_PART`, 
    `T_FORMATIONS`.`FOR_MAX_PART`, 
    `T_FORMATIONS`.`FOR_PRIX`, 
    `T_FORMATIONS`.`FOR_LANGUE` 
FROM `T_FORMATIONS` 
INNER JOIN `T_SESSIONS` 
    ON `T_FORMATIONS`.`FOR_ID` = `T_SESSIONS`.`SES_FOR_ID` 
INNER JOIN `T_COURS` 
    ON `T_SESSIONS`.`SES_ID` = `T_COURS`.`COU_SES_ID` 
WHERE `T_SESSIONS`.`SES_ETAT` = 1 
ORDER BY `T_COURS`.`COU_DATE` ASC, `T_SESSIONS`.`SES_TITRE` ASC, `T_FORMATIONS`.`FOR_TITRE` ASC 
LIMIT 5