What Data Type Is Serial Primary Key?


Larry Thompson

A serial primary key is a data type in relational databases that is used to uniquely identify each record in a table. It is an auto-incrementing integer value that automatically generates a new value for each new record inserted into the table.

What is a Primary Key?

In a relational database, a primary key is a column or combination of columns that uniquely identifies each row in a table. It ensures data integrity and provides a way to efficiently search and retrieve records from the table.

Serial Data Type

The serial data type in databases, such as PostgreSQL, is an extension of the integer data type. It allows you to automatically generate unique integer values for the column without having to manually assign them.

The serial data type is commonly used for primary keys because it guarantees uniqueness and avoids conflicts when multiple users are inserting records into the table simultaneously.

Auto-Incrementing Values

When you define a column with the serial data type as the primary key, the database system automatically assigns an incrementing value to each new record inserted into the table. The initial value is typically set to 1, and subsequent values increment by 1 for each new record.

Creating a Serial Primary Key

To create a serial primary key in PostgreSQL, you can use the SERIAL keyword when defining the column:

CREATE TABLE example_table (

The SERIAL keyword instructs PostgreSQL to create an auto-incrementing integer column. The PRIMARY KEY constraint ensures that this column serves as the primary key for the table.

Benefits of Using Serial Primary Keys

Using serial primary keys offers several benefits:

  • Uniqueness: Each record in the table is guaranteed to have a unique identifier.
  • Ease of Use: The database system automatically generates and assigns values, eliminating the need for manual input.
  • Efficient Queries: Serial primary keys allow for efficient indexing and retrieval of records from the table.
  • Data Integrity: They ensure the integrity of your data by enforcing uniqueness constraints.


A serial primary key is a data type in relational databases that provides an auto-incrementing integer value for uniquely identifying records in a table. It offers simplicity, efficiency, and data integrity benefits, making it a popular choice for primary keys. By utilizing the serial data type and setting it as a primary key constraint, you can ensure that each record in your table has a unique identifier without the need for manual intervention.

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