Example of declaring a continue handler in MySQL and rolling back or committing, based on status of _rollback

test_rollback_proc.sql

DROP PROCEDURE IF EXISTS test_rollback_proc;

DELIMITER //

CREATE PROCEDURE test_rollback_proc()
BEGIN

    DECLARE `_rollback` BOOL DEFAULT 0;
    DECLARE CONTINUE HANDLER FOR SQLEXCEPTION SET `_rollback` = 1;

    START TRANSACTION;

    /* SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'Custom error'; */
    
    IF `_rollback` THEN
        SELECT 'rolling back' AS status;
        ROLLBACK;
    ELSE
        SELECT 'committing' AS status;
        COMMIT;
    END IF;

END//

DELIMITER ;

CALL test_rollback_proc();