database master second semester

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...............................difference between super keys and candidate keys..........................................
Super Keys Candidate keys
1)A single attribute or a set of attributes that uniquely identifies all attributes in a relation is super key. 1) A proper subset of a super key, which is also a super key is a candidate key.
2)It is not compulsory that all super keys will be candidate keys. 2)All candidate keys are super keys.
3)The set of super keys forms the base for selection of candidate keys. 3)The set of candidate keys form the base for selection of a single primary key.
4)There are comparatively more super keys in a relation. 4)There are comparatively less candidate keys in a relation.

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