What is Entity-Set and Keys?
Key is defined as an attribute or set of attributes that uniquely points out an entity among entity set.
For instance, the roll_number of a student makes him/her identifiable among students.
1. Super Key: It is a set of attributes one or more that cooperatively distinguishes an entity in an entity set.
2. Candidate Key: This is a minimal super key. An entity set may contain more than one candidate key.
3. Primary Key: Primary key is one of the candidate keys selected by the database designer to uniquely and distinctively identify or point out the entity set.
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