How to check difference in each on OLD.* to NEW.* column in a MySQL Trigger?

Since SQL does not have a FOR-EACH statement, how could we verify if there is a difference on each value from the OLD object to the NEW object in a AFTER UPDATE type TRIGGER without knowing the table columns [and table names]?

Example today:

CREATE TRIGGER `audit_events_ugly`
AFTER UPDATE ON `accounts`
FOR EACH ROW
BEGIN
       DECLARE changes VARCHAR(8000);
       IF OLD.user_name <> NEW.user_name THEN
            SET changes = 'user_name from % to %';
       END IF;
       IF OLD.user_type <> NEW.user_type THEN
            SET changes = CONCAT(changes, ', user_type from % to %');
       END IF;
       IF OLD.user_email <> NEW.user_email THEN
            SET changes = CONCAT(changes, ', user_email from % to %');
       END IF;
       CALL reg_event(how_canI_get_tableName?, @user_id, changes);
       -- and that can go on and on... differently for every table.
END;

Example as I wish it could be:

CREATE TRIGGER `audit_events_nice`
AFTER UPDATE ON `accounts`
FOR EACH ROW
BEGIN
       DECLARE changes VARCHAR(8000);
       DECLARE N INT DEFAULT 1;
       FOREACH OLD, NEW as OldValue, NewValue 
       BEGIN
              IF OldValue <> NewValue THEN
              SET changes = CONCAT(changes, ', column N: % to %');
              SET N = N + 1;
       END IF;
       CALL reg_event(how_canI_get_tableName?, @user_id, changes);
       -- now I can paste this code in every table that is audited..
END;

Any Ideas? WHILE, FOREACH, ARRAYS...

I think you cannot do that directly in a for-loop at the trigger level.

However, you could use a script to generate the trigger code. You would need to re-generate it every time you add/remove a field to the table (usually not frequently).