mysql数据库表设计

Question

I have to design a database for an advert site. Until now this is the design i came up with:

Administrator(Id,Name,Password)

Advert(Advert_Id,Title,Description,Category,User,Date_created,Picture,Type)

User(User_Id, Name ,Phone,email,Address)

Category(Cat_id,Cat_Name)

Type(Id,Type_Name)

Picture(Picture_Id,Name)

The administrator refers to to the person that will manage the site.

The type refers to the type of the advert: selling, buying etc.

I am trying to keep it at simple as possible.

I must have minimum 5 tables at least 2 one to many relationships and at least one many to many relationship.The problem is that i can't find a many to many relationship that would make sense. Please help me with a few suggestions and tell me if i am doing something wrong.

Answer 1

If an advertisement can have more than one category, then advertisements and category would be many to many.

If an ad can have more than one picture and a picture can be used in more than one ad, ads and pictures would be many to many.

However, you have to know the business rules. None of us will.

Answer 2

Like Dan mentioned on the answer, you have to know the Business Rules. It's a project for a class, so the business rules might be flexible, I remember back in college, for example, they would tell us that if a client wanted to have advertisement be of at least one category, but could have up to 3 or 4 different categories, that changes your DB structure a lot.

An advertisement can also have many pictures, not just one. It can even have some videos, and many of them as well. Make sure you clarify well the Business Rules and that you understand them fully, as in a real life situation, that can represent either the success of your project or the failure of it.