Can someone please clarify something that I still need to know? If I have three surviving organizations, directors and company secretaries and everyone has primary primary address, I If I was modeling a conceptual ERD then I would have to separate each unit Should be the property of 'primary address' or should I know the fourth institution, the primary address should be added and they have to do PK> FK? / P> Since then, this link has been found which I want to know everything. I will do something like this, the primary address refers to the location of the organization: Table: Organization Org_Key {PK}, Org_Name, Primary Address Field, Any Other Fields Table: Personnel Person_Key {PK}, Org_Key {FK}, Status {Directory, Secretary, etc.}, Any other field In my opinion, in fact There is no need to separate people who are "secretaries" because they are "directors" because they Both employees of a specific organization. Now, i...