As this figure, if I write the relationship between students and express "belong to" a relational model, cannot be combined with express company attributes as key right? That I am not the ER chart will convert many table? In order to reduce the number of tables, I can connect the delivery company and the "return", the "send a member" and "relationship between the" express company to delete? As a contact link up with the four entities, should be no problem, right?

CodePudding user response:

Watch more than not, is mainly must conform to the actual demand, need not to need the data, such as sending a member, if you don't need that can be deleted