the work flows and how to design an er model or diagram

Question

i am trying to design an ER diagram or model of a dvd rental system but i am having problems with the design i have so far i want to put an entity for an administrator so that he can see everything and i also want to modify the customer entity so that the customer can only see what what is in the shop and not everything ,the customer can only check the basics here is my ER MODEL below

Answer 1

All users have to have privileges to access the database. The Privileges are dependant on the user.The basic privileges are.

 SELECT | gives the right to read the table contents.
 INSERT | gives the right to add new rows to the table.
 DELETE | gives the right to remove rows from the table.
 UPDATE | gives the right to update the contents of the table.

The customer will have SELECT maybe UPDATE to any table required for his part of the application.

The application administrator can have all the privileges above to all the tables in the application database.

The database administrator will have all the privileges in the database and will GRANT privileges to customer & application administrator

This is a very simplified version and you should research further, especially the database being used