What Data Type Is Serial?


Angela Bailey

What Data Type Is Serial?

When working with databases, you may come across the term “serial” in relation to data types. It is an essential concept to understand, as it plays a crucial role in the organization and manipulation of data.


The “serial” data type is specific to certain database management systems, such as PostgreSQL. It is used for creating auto-incrementing numeric columns. In other words, when a new row is inserted into a table with a serial column, the database system automatically assigns a unique value to that column.


The serial data type is commonly used when you want to ensure that each row in a table has a unique identifier. This is particularly useful when working with tables that do not have any natural keys or when you need a primary key that automatically increments.

To create a serial column in PostgreSQL, you can use the following syntax:

CREATE TABLE table_name (
    column_name SERIAL PRIMARY KEY,

In this example, the SERIAL keyword is used to define the data type of the column_name. The PRIMARY KEY constraint ensures that the values in this column are unique and not null.


  • The actual underlying data type of a serial column is an integer.
  • The value assigned to a new row in a serial column is generated by an internal sequence generator maintained by the database system.
  • You can also specify additional constraints or modifiers on serial columns, such as NOT NULL, UNIQUE, or DEFAULT.


The use of serial data types offers several advantages:

  • Simplicity: It simplifies the process of assigning unique identifiers to each row.
  • Efficiency: The automatic incrementation of serial columns is performed efficiently by the database system, eliminating the need for manual intervention.
  • Data Integrity: Serial columns with primary key constraints ensure the uniqueness and integrity of the data in a table.


In summary, the serial data type is a valuable tool when working with databases that require auto-incrementing numeric columns. It provides simplicity, efficiency, and data integrity, making it an essential component in database design and management.

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