I have a situation where customers can rent bikes. They are charged a one off annual fee. They are also charged when they rent a bike based on how long they had it (different rates for different lenght of times.). I'm thinking of having a seperate table for the annual fee and then a table to for each rental. The problem is i'm not sure how to link the fee table. I've attached a pic of what i've done so far. Any help would be greatly appreciated.