A super key in a database management system (DBMS) is a set of one or more attributes that can uniquely identify a record within a table. It is a broader concept than the primary key and can include additional attributes beyond what is required for uniqueness. Super keys are important during the database design phase for identifying potential candidate keys, from which the primary key is chosen.
Here are some key points about super keys in DBMS:
- A super key is a group of single or multiple keys that identifies rows in a table.
- All candidate keys come under the bracket of super keys.
- The set of all super keys is a superset of all candidate keys.
- Super keys are used for functional dependency determination and normalization.
- A super key can be used for primary key selection and uniqueness constraint.
- A super key can be a composite key made up of multiple attributes.
- Super keys can include attributes beyond what is required for uniqueness.
- All primary/candidate keys are super keys, but not all super keys are primary/candidate keys.
In summary, a super key is a collection of all keys that can uniquely identify rows of a table. It is a crucial concept in DBMS that acts as a foundation for concepts like primary keys, candidate keys, normal forms, and more.
