Question

Define primary key? ☺ ☺

Answer 1

Explanation:

primary key is a specific choice of a minimal set of attributes that uniquely specify a tuple in a relation. Informally, a primary key is "which attributes identify a record", and in simple cases are simply a single attribute: a unique id.

Answer 2

Explanation:

In the relational model of databases, a primary key is a specific choice of a minimal set of attributes that uniquely specify a tuple in a relation. Informally, a primary key is "which attributes identify a record," and in simple cases constitute a single attribute: a unique ID.