If you have an update trigger in Oracle and want to check if value of specific field has changed, use (note the single quotes around field name)
IF UPDATING('MyField') THEN
If you try to use
IF UPDATING(:NEW.MyField) THEN
it will not work, as :NEW.MyField value hasn’t actually changed, so the check will always return false.
You can also compare old and new values
IF :NEW.MyField != :OLD.MyField THEN