Practice mode DBMS and SQL

Which statement best describes a candidate key?

Correct answer C. A minimal superkey, with no proper subset that is also a superkey

Explanation

A superkey is any set of attributes that uniquely identifies a tuple. A candidate key is a superkey with nothing redundant: removing any attribute destroys uniqueness. One candidate key is chosen as the primary key and the rest become alternate keys. The first option describes superkeys in general, which may contain extra attributes; the third describes a foreign key.

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Which statement best describes a candidate key?

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Which statement best describes a candidate key?

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