A primary key is a composite key that was selected to be the main identifier for the relation.

More Questions from The Relational Model and Normalization

• A relation is a two-dimensional table.
• The only reason for the existence of relations is to store instances of functional dependencies.
• Given the functional dependency R → (S,T) , then it is also true that R → S.
• A relation is in Boyce-Codd Normal Form (BCNF) if every determinant is a composite key.
• Any table that meets the definition of a relation is said to be in first normal form.
• In a relation, the order of the rows matters.
• Given the functional dependency R → S , R is called the determinant.
• In a relation, the rows are sometimes called "records."
• In a relation, the order of the columns does not matter.
• A relation has cells that hold multi-value entries.

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