The Problem of Overwriting a Value to the Same Record

Application logic requires that the two doctors be on call, but it's not a database constraint. So you can get into this situation. The other problem of writing, overwriting a value to the same record is where application logic is bleeding into your storage layer. But I was thinking in my head like, well, I wonder if there's a better place, you know, a better way that you could structure that type of need.