Question

Short notes on primary key​

Answer 1

Answer:

A primary key is a special relational database table column (or combination of columns) designated to uniquely identify each table record. A primary key is used as a unique identifier to quickly parse data within the table. A table cannot have more than one primary key.

Primary Key.

Candidate Key.

Alternate Key.

Super Key.

Composite Key.

Foreign Key.

Unique Key.

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.

Explanation: