mysql - SQL Where 子句中的 If/Else

Question

我想在 SQL 查询的 WHERE 子句中使用 IF 条件。但比较应该来自另一个表的列。简单来说，我的伪代码是这样的:

SELECT * FROM TABLE1
WHERE
 (if DATE from TABLE2 = 0000 then select ID from TABLE2 as TABLE1.ID 
 else if ID from TABLE2 = 00 then select DATE from table2 as TABLE1.DATE)

感谢您的帮助。

Answer 1

您的伪代码非常模糊，但据我了解，类似这样的代码应该有效:

SELECT TABLE1.* 
FROM TABLE1
INNER JOIN TABLE2 
   ON   (TABLE2.DATE = '0000' AND TABLE1.ID = TABLE2.ID)
     OR (TABLE2.ID = '00' AND TABLE2.DATE = TABLE1.DATE)

参见this fiddle .