MySQL Trigger usage : if column is null set other column null

Question

How do I realize the following in MySQL with Triggers: When value of some column is null -> set other column values to null
and when value of some column is not null -> set other column values to null

table definition:

CREATE TABLE variations (  
id int(10) NOT NULL, 
x1 int(10) NOT NULL, 
x2 int(10), 
x1_option1 BOOL, 
x2_option1 BOOL, 
x1_option2 varchar(10), 
x2_option2 varchar(10)
);

The idea is that we have 2 Elements, x1and x2. While x1is mandatory, x2is optional and can be null. Both, x1 and x2 have two options: x1_option1 , x2_option1, x1_option2 and x2_option2.
The first rule should be that when x2 is null, both options for x2 (x2_option1, x2_option2) must also be null.
My attempt:

CREATE 
TRIGGER check_null_x2 BEFORE INSERT 
ON variations
FOR EACH ROW BEGIN
IF NEW.x2 IS NULL THEN 
SET NEW.x2_option1 = NULL;
SET NEW.x2_option2 = NULL;
END IF;
END$$

Throws Error:

#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 '' at line 6 

Can you please help me figuring out whats wrong? I just dont understand what '' means.

The second rule should be that there can only be one of the two options selected. that means if x2_option1 is NOT NULL, x2_options2 must be NULL. In general i think this can be done the same way as the first rule. My question: how can i do multiple 'IF', 'ELSE IF' etc in one trigger?

Answer 1

This is syntax for trigger:

delimiter //
CREATE TRIGGER upd_check BEFORE UPDATE ON account
     FOR EACH ROW
     BEGIN
         IF NEW.amount < 0 THEN
             SET NEW.amount = 0;
         ELSEIF NEW.amount > 100 THEN
            SET NEW.amount = 100;
         END IF;
    END;//
 delimiter ;

...and your code is here:

DELIMITER //
CREATE TRIGGER check_null_x2 BEFORE INSERT ON variations
    FOR EACH ROW
    BEGIN
        IF NEW.x2 IS NULL THEN 
            SET NEW.x2_option1 = NULL;
            SET NEW.x2_option2 = NULL;
        END IF;
    END$$ -- THIS LINE SHOULD BE: "END;//"
DELIMITER ;

Answer 2

you seem to have ";" set as DELIMETER, which causes the query to execute once it sees a ";". try changing it first:

DELIMITER //
CREATE 
TRIGGER check_null_x2 BEFORE INSERT 
ON variations
FOR EACH ROW BEGIN
IF NEW.x2 IS NULL THEN 
SET NEW.x2_option1 = NULL;
SET NEW.x2_option2 = NULL;
END IF;
END;//
DELIMITER ;