Implement specialization in ER diagram

Question

I want to implement this specialization relationship  Knowing that I will have different attributes for each account type  Here s my try   accounts account id  email  username  password       user accounts account id      admin accounts account id      messages subject  body  from account id  to account id    Where account id in user accounts and admin acounts is the primary key and foreign key references account id on accounts And from account id  to account id in messages references account id on accounts   But what happens if I wanted to create a relationship with one of the account type only  For example I want to give permissions to admins to manage something  So I would do something like this   permissions admin account id  type  value        Where admin account id is a foreign key references account id on admin accounts  Is that possible  And what would happen If I tried to enter a permission for a user account id instead   I hope my question is clear and excuse my English language

User · Answer

So I assume your permissions table has a foreign key reference to admin accounts table  If so  because of referential integrity you will only be able to add permissions for account ids exsiting in the admin accounts table  Which also means that you wont be able to enter a user account id  assuming there are no duplicates

[mysql] Implement specialization in ER diagram

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