Question

A minimal super key (i.e., one of the super keys for which no proper subset is a super key) is called:
1. Super Key
2. Candidate Key
3. Primary Key
4. Both Candidate and Primary Key

Answer 1

Correct Answer - Option 4 : Both Candidate and Primary Key

• A candidate key is a minimal super key or a super key with no redundant attribute.
• It is called a minimal super key because we select a candidate key from a set of super keys such that the selected candidate key is the minimum attribute required to uniquely identify the table.
• It is selected from the set of the super key which means that all candidate keys are super key.
• Candidate Keys are not allowed to have NULL values.
• Primary key is selected from the set of candidate keys and hence A minimal super key is called Candidate and Primary Key