ALTER TABLE `vn`.`ticketLog` 
DROP FOREIGN KEY `ticketLog_ibfk_2`;
ALTER TABLE `vn`.`ticketLog` 
CHANGE COLUMN `userFk` `userFk` INT(10) UNSIGNED NULL DEFAULT NULL ;
ALTER TABLE `vn`.`ticketLog` 
ADD CONSTRAINT `ticketLog_ibfk_2`
    FOREIGN KEY (`userFk`)
    REFERENCES `account`.`user` (`id`)
    ON DELETE CASCADE
    ON UPDATE CASCADE;