mysql - mysql中的IF条件

Question

我有一个联系人表，我希望在存在特定条件时查询。我尝试了下面的查询，但出现语法错误。

SELECT * 
FROM   contact_details 
WHERE  contactDeleted` =0 
AND    IF ( contactVisibility = "private"
           ,  SELECT * FROM contact_details
              WHERE    contactUserId = 1 
           , IF( contactVisibility = "group"
                ,  SELECT * FROM contact_details  
                   WHERE contactGroup = 3 
               ) 
          )

Answer 1

如果我正确理解了您的问题(由于您提供的信息不足，这很困难。示例数据集和预期结果通常会有所帮助)，那么我认为您根本不需要 IF 来实现您想要的.以下将返回未删除的联系人以及具有 (visibility = "private"and userId = 1) OR (visibility = "group"and group = 3)

SELECT * 
FROM contact_details 
WHERE contactDeleted = 0 
    AND ( 
        (contactVisibility = "public") 
        OR
        (contactVisibility = "private" AND contactUserId = 1) 
        OR 
        (contactVisibility = "group" AND contactGroup = 3)
    )