Seems to me it makes more sense to keep Bob in the list. If you take him out then if you query for a list of members for any date between 2015-02-20 and 2017-08-07, your list would be incomplete. Also, how do we know from the data that Bob was dropped from the roster -- he might be in the same state Richard was before the updates. His end date was recorded, but his new status hasn't been added yet. Anyway, here's my solution.