Mysql如果存在则更新else插入

Question

我在Sql server上使用此命令插入值，如果id已存在则更新该值

string commandLine = "IF NOT EXISTS(SELECT clientid FROM Rating WHERE clientid = " + clientId + " AND userid = " + userid + ") " +
            "INSERT INTO Rating VALUES(@clientId,@userid,@rating) " +
            "ELSE " +
            "UPDATE Rating SET rating=@rating WHERE clientid = " + clientId + " AND userid = " + userid + ";";

我现在转向MySQL ，这个命令不起作用。 MySQL中有什么相同的东西吗？

Answer 1

INSERT ... ON DUPLICATE KEY UPDATE在MySQL中提供了等效的语法。

Answer 2

如果您在clientid上有唯一约束或主键，则可以使用INSERT ... ON DUPLICATE KEY UPDATE语法

INSERT INTO Rating VALUES(@clientId,@userid,@rating)
ON DUPLICATE KEY
UPDATE Rating SET rating=@rating