Getting started with PostgreSQL SERIAL

PostgreSQL serial data type is used to define the auto-increment number of columns in a table, PostgreSQL serial will generate a serial sequence of integer numbers.

A sequence is mainly used as the primary key column in a table.

Serial data types are not actual types, but merely a notational convenience for creating non-nullable integer columns with sequences attached.

PostgreSQL has three serial types

• SMALLSERIAL 2 bytes 1 to 32,767

• SERIAL 1 to 2,147,483,647

• BIGSERIAL 8 bytes 1 to 9,223,372,036,854,775,807

We can create a table using serial as follows: 

CREATE TABLE user (
    id SERIAL
);

if you want a serial column with a unique constraint or a primary key it should be specified like any data type in PostgreSQL.

CREATE TABLE user(
   ID  SERIAL PRIMARY KEY,
   name           TEXT      NOT NULL,
   surname        TEX       NOT NULL,
 );