Say I have cattle: cows and bulls, and I have five (5) camps on a given farm. The ration of bull:cow is 1:(25-30) for a given period of say two month or so. A camp can only host one group for given period. I attempted to draft the attached ERD. Which table am I going to base my layout on if I want to have a portal from where I will select the available cows and a bull for camp A, B, C, D or E etc. I am trying my best to make sense of my user requirements, I hope it is clear.