在 Sql server 中,我使用这个命令插入值,并在 id 已存在时更新该值。
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 + ";";
我现在转向使用MySQL
,但这个命令不起作用了。在MySQL中有类似的东西吗?