I need answer for b please Does the above relation have a

I need answer for ( b ) please

Does the above relation have a potential candidate key? If it does, what is it? If it does not, why not?

Solution

Candidate Key:

A minimal set of columns/attributes that can be used to uniquely identify a single row/tuple in a given relation, is called candidate key.

It can be identified during design time.

By knowing the candidate key,

Database designers selects one of the candidate keys as primary key.