Either new-start-date must be between promo-start-date and promo-end-date, or new-end-date must be between promo-start-date and promo-end-date. At least if my meaning for "overlapping" is the same as yours. (Mine permits the new date range to be entirely within the old date range.)
Joined: Nov 10, 2005
mine is more complicated compared to just overlap. new start date or new end date cannot be in between of old start date and old end date, that's one, another thing is the new start date is before the old start date and also the new start date is after the old end date. so it's like the old period of time becomes a subset of the new period of time.