Super Key:
1. A set of attributes (columns) that uniquely identifies each record in a table.
2. Can be a single column or a combination of columns.
3. May contain additional attributes beyond what's necessary for uniqueness.
Candidate Key:
1. A minimal set of attributes (columns) that uniquely identifies each record in a table.
2. Cannot be reduced further without losing uniqueness.
3. Meets the requirements of a primary key.
Key differences:
- A Super Key can have extra attributes, while a Candidate Key is minimal.
- A Candidate Key is a special type of Super Key that meets primary key requirements.
To illustrate the difference:
- Super Key: {Employee ID, Name, Department} (Employee ID alone is enough, but Name and Department are included)
- Candidate Key: {Employee ID} (minimal set that uniquely identifies each record)
In summary, all Candidate Keys are Super Keys, but not all Super Keys are Candidate Keys. Candidate Keys are the most suitable options for primary keys.#cbse
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