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What is the use of primary key in SQL?

Contents
  1. Why primary key is used in SQL?
  2. What is the purpose of a primary key?
  3. What is the use of primary and foreign key in SQL?
A primary key is a field in a table which uniquely identifies each row/record in a database table. Primary keys must contain unique values. A primary key column cannot have NULL values.


Why primary key is used in SQL?

The PRIMARY KEY constraint uniquely identifies each record in a table. Primary keys must contain UNIQUE values, and cannot contain NULL values. A table can have only ONE primary key; and in the table, this primary key can consist of single or multiple columns (fields).

What is the purpose of a primary key?

The main purpose of a primary key is to implement a relationship between two tables in a relational database; it's not called a relational database for nothing! More specifically, the primary key is the "target" which a foreign key can reference.

What is the use of primary and foreign key in SQL?

A primary key is used to assure the value in the particular column is unique. The foreign key provides the link between the two tables.

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