MySQL: condition between two columns - mysql

Question

I have two columns:
commission (percental('yes','no'))
recurring(enum('yes','no').
I want to declare the following dependency:
recurring can only be 'yes', when percental is 'yes', too.
Is there a possibility to manage it within mysql?

Answer 1

you could create two triggers to check for this, sqlfiddle
CREATE
TRIGGER `before_insert` BEFORE INSERT
ON `commission`
FOR EACH ROW BEGIN
IF NEW.recurring = 'yes' AND NEW.percental != 'yes' THEN
signal sqlstate '45000' set message_text = "percental must be 'yes' for recurring to be 'yes'";
END IF;
END/
CREATE
TRIGGER `before_update` BEFORE UPDATE
ON `commission`
FOR EACH ROW BEGIN
IF NEW.recurring = 'yes' AND NEW.percental != 'yes' THEN
signal sqlstate '45000' set message_text = "percental must be 'yes' for recurring to be 'yes'";
END IF;
END/
since the code is the same for UPDATE and INSERT you might want to create a procedure to call for both triggers like this sqlfiddle
DROP PROCEDURE IF EXISTS check_commission_recurring_based_on_percental/
CREATE PROCEDURE check_commission_recurring_based_on_percental(IN percental ENUM('yes','no'), IN recurring ENUM('yes','no'))
BEGIN
IF recurring = 'yes' AND percental != 'yes' THEN
signal sqlstate '45000' set message_text = "percental must be 'yes' for recurring to be 'yes'";
END IF;
END/
CREATE
TRIGGER `before_insert` BEFORE INSERT
ON `commission`
FOR EACH ROW BEGIN
CALL check_commission_recurring_based_on_percental(NEW.percental,NEW.recurring);
END/
CREATE
TRIGGER `before_update` BEFORE UPDATE
ON `commission`
FOR EACH ROW BEGIN
CALL check_commission_recurring_based_on_percental(NEW.percental,NEW.recurring);
END/