问题
I have the following relationships (Business rules):
- User_Company : Many-to-many (multiple companies per user, multiple users per company)
- Ownership : One-to-One (For each entry in relationship table, it specifies whether user is an owner or employee. If owner then a percentage must be there)
- Company_ownership : One-to-many for company (Recursive relationship), as another company can also be an owner in a company, percentage must be given.
So ownership or a company can be made up of a number of companies and users.
So I have developed the following:
So does there have to be at least 4 tables for this sort of relationship or can it be simplified. I feel it is quite complicated and would not be intuitive for another developer? How could it be optimized and elegantly arranged?
回答1:
I think ownership and employment are different concepts, that would be more advised to have them separated.
Think about John who is one of the owners of A company and in the mean time he is the CTO of A.
Company and People can have a base to reduce redundancy of entities.
回答2:
Based on the suggestions of Thilo
A separate relationship table was created for owners and employees respectively.
Furthermore, the company_ownership and ownership tables were removed as having a company as an owner is solved by adding an owning_user_id and owning_company_id where one will always be null. The percentage figure is added to this relationship table.
See below:
来源：https://stackoverflow.com/questions/21450640/does-a-many-to-many-relationship-with-a-recursive-one-to-many-in-mysql-require-a