I'm a student who currently studying database systems, so I have some doubts on designing a database system.

I'm currently designing a car wash center database, which has a manager and car washers

1. When I am developing an ER diagram, am I going to include a box with "Center" as a weak entity which is related to a box "EMPLOYEE"?

2. If I include an EMPLOYEE inside the ER diagram, can I use supertype to joint out the manager and car washer?

3. If so, can both entity have relationships with other entities? Because what I've read on my book it doesn't have any complete ER diagram with supertype.


Appreciate with answers.

If you are familiar with oracle refer to EMP table of SCOTT schema for start up.

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