mysql - MYSQL 触发器语法问题

Question

我正在尝试这个触发器，但它一直给我这个错误：

扳机

DELIMITER $$
CREATE
TRIGGER entries_limit_trigger
BEFORE INSERT ON Feed
FOR EACH ROW
BEGIN
Set @counts=(SELECT count(*) from Feed);
IF (@counts > 10000)
THEN
PRINT 'INSERTED SUCCESS';
END IF; 
END
$$
DELIMITER ;

错误

#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''INSERTED SUCCESS'; END IF; END' at line 9

Answer 1

如果您希望触发器退出并显示一条消息，您可以执行以下操作：

CREATE
TRIGGER entries_limit_trigger
BEFORE INSERT ON Feed
FOR EACH ROW
BEGIN
Set @counts=(SELECT count(*) from Feed);
IF @counts > 10000 THEN
  set @msg = "Reached the limit";
  SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = @msg;
END IF; 
END;

sqlfiddle demo

要让它退出一条消息，只需在小提琴中添加另一个插入。