MySQL - At least one column must have a value

trigger.sql

/*
|--------------------------------------------------------------------------
| At least one column must have a value
|--------------------------------------------------------------------------
|
| This is a simple pair of triggers for MySQL databases that will disallow
| a row to be inserted into a table unless at least one of two predefined
| columns has a value set.
|
*/

DELIMITER $$

CREATE TRIGGER InsertParentNotNull BEFORE INSERT ON content
FOR EACH ROW BEGIN
  IF (NEW.column_one IS NULL AND NEW.column_two IS NULL) THEN
    SIGNAL SQLSTATE "45000"
    SET MESSAGE_TEXT = "\"column_one\" and \"column_two\" cannot both be null";
  END IF;
END;

CREATE TRIGGER UpdateParentNotNull BEFORE UPDATE ON content
FOR EACH ROW BEGIN
  IF (NEW.column_one IS NULL AND NEW.column_two IS NULL) THEN
    SIGNAL SQLSTATE "45000"
    SET MESSAGE_TEXT = "\"column_one\" and \"column_two\" cannot both be null";
  END IF;
END