AUTO INCREMENT a Field in MySQL

Very often, we want to make columns as auto increment in Database. By specifying AUTO_INCREMENT to the primary key field, we can make column value as auto incrementing in MySQL.

The below code create a simple table “Employees” with a single auto increment column named as “ID”.

CREATE TABLE Employees
(
ID int NOT NULL AUTO_INCREMENT,
Name varchar(255) NOT NULL,
Address varchar(255),
City varchar(255),
PRIMARY KEY (ID)
);

By default, the starting value for AUTO_INCREMENT is 1, and it will increment by 1 for each new record.

If we want to start AUTO_INCREMENT column with another value, we can use the following SQL statement.

ALTER TABLE table_name AUTO_INCREMENT= [New Number];

The AUTO INCREMENT interval value is controlled by the MySQL Server variable auto_increment_increment and applies globally. To change this to a number different from the default of 1, we can use the following command in MySQL.

SET @@auto_increment_increment = [interval number];

To insert a new record into the “Employees” table, we will NOT have to specify a value for the “ID” column (a unique value will be added automatically):

INSERT INTO Employees (Name,City)
VALUES ('Blue','zzzzz');

The SQL statement above will insert a new record into the “Employees” table. The “ID” column would be assigned a unique value.

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This article was published on February 13, 2014

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