I think we need to know what the two date columns represent, so that we do not guess. It looks to me the update column is like a record time stamp, and irrelevant. Is this correct? If a customer enters status 1 on a day and leaves that status four hours later yet in the same day... do you want to count that as 0 days? What if the four hours take the status past midnight? Should you maybe be using a time portion to extract day fractions? This is part of your business rules that we may need to know.