Does anyone know of some good references to read up on regarding circular references (ie. why they're bad and how to resolve them)? It's been a while since I did a db course or worked in any depth with db structure and now I need the info for a side project. I know that circular refs are 'bad' but that's about the extent of my knowledge. I also Googled but I've got the wrong search terms because I couldn't find anything that seemed to relate (just stuff for code, not databases). Basically, I have 4 tables. Each table has a single field as PK. Each table also has a single FK which points to one other table's PK. It's a perfect little cirle, or square I guess. All of the relationships seem necessary to me, and the table structure is about as efficient as I can make it without redundancy. Since I might need to update any of those tables at any given time, I'm guessing I need to break the circle somewhere. At the end of the day I mainly want to avoid bad design. I'm writing an app on top of this and I don't want to be bit in the ass later. Please help me edjumacate myself!