MySQL trigger definition - 1064 error

问题

My proposed trigger:

#START TRIGGER
delimiter //
DECLARE msg VARCHAR(255);
CREATE TRIGGER passStandard_check BEFORE INSERT ON Module
FOR EACH ROW 
BEGIN 
IF NEW.passStandard < 0 || NEW.passStandard > 1 THEN 
set msg = concat('Trigger Error: Pass Standard: ', cast(NEW.passStandard as char));
signal sqlstate '45000' set message_text = msg;
END
//
delimiter ;
#END TRIGGER

But I get the following error:

Error Code: 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 'DECLARE msg VARCHAR(255); CREATE TRIGGER passStandard_check BEFORE INSERT ON Mod' at line 1

Adding in END IF does not make any difference.

passStandard is set to an INT NOT NULL.

---

Edit

I've moved the DECLARE statement after the BEGIN:

#START TRIGGER
delimiter //
CREATE TRIGGER passStandard_check BEFORE INSERT ON Module
FOR EACH ROW 
BEGIN 
DECLARE msg VARCHAR(255);
IF NEW.passStandard < 0 || NEW.passStandard > 1 THEN 
set msg = concat('Trigger Error: Pass Standard: ', cast(NEW.passStandard as char));
signal sqlstate '45000' set message_text = msg;
END IF;
END
//
delimiter ;
#END TRIGGER

But I still get this error:

Error Code: 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 'sqlstate '45000' set message_text = msg; END IF; END' at line 7

回答1:

You need to declare your variable "msg" inside your procedure and use END IF

#START TRIGGER
delimiter //
CREATE TRIGGER passStandard_check BEFORE INSERT ON Module
FOR EACH ROW 
BEGIN 
    DECLARE msg VARCHAR(255); /* << PUT THIS HERE */
    IF NEW.passStandard < 0 || NEW.passStandard > 1 THEN 
        set msg = concat('Trigger Error: Pass Standard: ', cast(NEW.passStandard as char));
        signal sqlstate '45000' set message_text = msg;
    END IF; /* << YOU WILL NEED THIS TOO (DONT FORGET THE SEMICOLON :D) */
END//
delimiter ;
#END TRIGGER

回答2:

I noticed that I was getting MySQL warnings when adding triggers with IF/ELSE logic in them if I wasn't adding parentheses to the IF statements. Not sure why, but I added the brackets and the warnings went away. Try something like:

IF ((NEW.passStandard < 0) || (NEW.passStandard > 1)) THEN 
    set msg = concat('Trigger Error: Pass Standard: ', cast(NEW.passStandard as char));
    signal sqlstate '45000' set message_text = msg;
END IF;

回答3:

Try breaking it up to several queries. Or run it in phpmyadmin which handles semi colon separated multi queries.

回答4:

Might be this:

DECLARE is permitted only inside a BEGIN ... END compound statement and must be at its start, before any other statements.

http://dev.mysql.com/doc/refman/5.0/en/declare.html

回答5:

i got it working. pls find below the working code.

delimiter //
CREATE TRIGGER test_check1 BEFORE INSERT ON employee 
FOR EACH ROW 
BEGIN
DECLARE msg VARCHAR(255); 
IF (NEW.sync_id = '0') THEN 
SET NEW.name = 'Collect Money'; 
signal sqlstate '45000' set message_text = msg; 
END IF; 
END//
delimiter ;

来源：https://stackoverflow.com/questions/9042229/mysql-trigger-definition-1064-error