Primary Key

The chosen candidate key that uniquely identifies every row and cannot contain NULL.

What is Primary Key in a relational database?

Primary Key — The chosen candidate key that uniquely identifies every row and cannot contain NULL.

CREATE TABLE customer (
    customer_id INTEGER PRIMARY KEY,
    email CHARACTER VARYING(255) NOT NULL,
    status CHARACTER VARYING(20) DEFAULT 'active'
);

Level: Novice · More Database terms at this level

Updated September 27, 2026