Mysql 如果存在则更新，否则插入不起作用

我需要有关SQL过程的帮助。我已经尽我所能尝试了，但以下程序不起作用，需要帮助为什么不起作用

CREATE PROCEDURE updateUser
     (IN ID INT(11), 
      name VARCHAR(100), 
      email VARCHAR(100), 
      role VARCHAR(9), 
      gender VARCHAR(6), 
      birthday VARCHAR(10), 
      classroom INT(11) )  

   SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;

   BEGIN TRANSACTION;
       IF EXISTS (SELECT * FROM student WHERE userID = ID)
       BEGIN
           UPDATE tbl_users 
           SET userName = name, userEmail = email, userRole = role, 
               gender = gender, birthday = birthday 
           WHERE userID = ID;

           UPDATE student 
           SET classID = classroom 
           WHERE userID = ID;
       END
       ELSE
       BEGIN
           UPDATE tbl_users 
           SET userName = name, userEmail = email, userRole = role, 
               gender = gender, birthday = birthday 
           WHERE userID = ID;

           INSERT INTO student(classID, userID) 
           VALUES (classroom, ID);
       END

       COMMIT TRANSACTION;

---

上面的“更新到学生查询”和“插入到查询”都是单独工作的。但在插入

IF EXISTS

时不可用

因为您正在使用MySQL。试试下面的代码，看看它是否有效

CREATE PROCEDURE updateUser
     (IN ID INT(11), 
      name VARCHAR(100), 
      email VARCHAR(100), 
      role VARCHAR(9), 
      gender VARCHAR(6), 
      birthday VARCHAR(10), 
      classroom INT(11) )  


   BEGIN
       IF EXISTS (SELECT * FROM student WHERE userID = ID) THEN
       START TRANSACTION;
           UPDATE tbl_users 
           SET userName = name, userEmail = email, userRole = role, 
               gender = gender, birthday = birthday 
           WHERE userID = ID;

           UPDATE student 
           SET classID = classroom 
           WHERE userID = ID;
       COMMIT;
       ELSE
       START TRANSACTION;
           UPDATE tbl_users 
           SET userName = name, userEmail = email, userRole = role, 
               gender = gender, birthday = birthday 
           WHERE userID = ID;

           INSERT INTO student(classID, userID) 
           VALUES (classroom, ID);

       COMMIT;
       END IF;
   END;

---

你的意思是不工作？有错误吗？错误行为？请澄清您的问题。当我尝试在不使用if语句的情况下更新student表时，数据未插入或更新到数据库中。它有效。但是当我使用if语句时，它不起作用。我看不出问题出在哪里。我的建议是做一些调试。测试

是否存在

是否在某些打印消息中正常工作。删除事务。从一些基本的开始，逐步积累，直到你发现问题所在。