I am building a database to keep track of promotions. For the most part it is pretty straight forward the promotion table will contain the promo ID, name, and several dates including the start and end date of the promotion. In some situations, but not all the promotion may fall under the umbrella of another "parent" promotion. If this were a situation where there was a parent for every promotion I would create two tables (master and detail) and put data that differs from one "child" promotion to the next in the detail table. But since not every "child" has a parent I am wondering if I should just keep them all in one table and flag which ones are "parent" promotions.
Your thoughts and/or suggestions are appreciated.