在MySQL中是有可能写出加入取决于如果条件

，如：在MySQL中是有可能写出加入取决于如果条件

SELECT * FROM (`expenditures`) 
JOIN `categories` 
ON `categories`.`cat_id` = `expenditures`.`cat_id` IF(`projects`.`project_id` ! = 0) 
JOIN `projects` 
ON `projects`.`project_id` = `expenditures`.`project_id` 
WHERE `expenditure_id` = $expenditure_id

来源

2016-02-29 lokesh sahu

的可能的复制[如何使用IF语句一个MySQL连接查询？]（http://stackoverflow.com/questions/10064183/how-do-i-use-an-if-statement-in-an-mysql-join-query） –

不，这是不可能的。你究竟想要完成什么？ – shmosel

你可以试试这个：

SELECT * FROM (`expenditures`) 
JOIN `categories` 
ON `categories`.`cat_id` = `expenditures`.`cat_id` 
JOIN `projects` 
ON `projects`.`project_id` = `expenditures`.`project_id` and `projects`.`project_id` ! = 0 
WHERE `expenditure_id` = $expenditure_id

来源

2016-02-29 05:43:20

SELECT * FROM (`expenditures`) 
JOIN `categories` 
ON `categories`.`cat_id` = `expenditures`.`cat_id` 
JOIN `projects` 
ON `projects`.`project_id` = `expenditures`.`project_id` and `projects`.`project_id` <> 0 
WHERE `expenditure_id` = $expenditure_id

来源

2016-02-29 05:46:05 FallAndLearn

在MySQL中是有可能写出加入取决于如果条件

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