Correct. But to track both directions, I'd use two timestamp columns: is_active and is_inactive with check constraint that only one of them can be non-null. Oth

Correct. But to track both directions, I'd use two timestamp columns: is_active and is_inactive with check constraint that only one of them can be non-null. Otherwise someone is likely to omit updating the “timestamp of the last change” in a hurry.