Auto_Increment MySQL Function: 4 Comprehensive Aspects

Abhinav Chola • Last Modified: December 29th, 2022

Auto_Increment MySQL

MySQL is a robust and popular DBMS (Database Management System) that allows you to manage your large datasets online in a hassle-free manner. However, MySQL like any other DBMS uses interconnected tables to manage data. These tables are connected via Primary and Foreign Keys. A lot of time and effort goes into generating unique primary keys for new data inputs to the MySQL platform. Businesses are thus drawn towards the Auto_Increment MySQL function to automate this whole process and save their time and resources.

Its scalability, flexibility, secure transaction service, and ability to integrate with external tools make it an ideal choice for today’s businesses. Moreover, it provides comprehensive support to application developers and facilitates automatic data processing. Business often deploys their databases on this platform to save the price overhead offsetting up their in-house DBMS and maintaining it.

The Auto_Increment MySQL function generates an increasing sequence of unique numbers that can collectively act as a primary key in a MySQL table. You need to manually implement this function while creating your table for the first time. Once you do that, it will take over and you never have to worry ver generating Primary Keys.

This article will introduce you to the MySQL platform and list down its key features. It will also define the Auto_Increment MySQL function and explain its working. The article will then list the importance of this feature and explain its easy-to-use syntax. Furthermore, it will elaborate on the usage of the Auto_Increment function through an example. Read along to master this beneficial MySQL function!

Table of Contents

What is MySQL?

Auto_Increment MySQL: MySQL Logo
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MySQL is a powerful DBMS launched worldwide in 1995. It uses SQL (Structured Query Language) to carry out record manipulation and other data-associated operations. MySQL is available as an open-source tool and is within the reach of everyone who desires to utilize its services.

However, there are certain advanced variations of MySQL, designed to fulfill your particular business requirements. You can enlist their services by paying a month-to-month fee.

Due to its multitude of in-built tools and features, businesses in recent times heavily rely upon the MySQL platform for scalable and secure management of their data. 

A huge advantage that MySQL has over its peers like Oracle databases and Microsoft SQL Serve, is its simplicity. Moreover, it empowers you to use any programming language, for free, while running operations with this DBMS platform.

Another key aspect of using MySQL lies in its capacity to integrate well with Linux, Unix, Windows, and other operating systems. Furthermore, MySQL helps you to pick out its mode of implementation so that you can both use it online or after loading it to your nearby device.

Key Features of MySQL

The following key features make MySQL a popular DBMS choice: 

  • High performance: You can leverage the MySQL engine to have a great data management experience consisting of high processing rates coupled with an easy-to-learn user interface. Moreover, it allows you to serve numerous customers simultaneously by providing them with rapid and global MySQL access. 
  • Compatibility: MySQL ensures that your data transactions are secure and consume low latency. You can add on multiple web development tools using the MySQL platform and further enhance your data processing.  
  • Scalability: You can upscale or downscale your data needs anytime with the MySQL platform. Furthermore, it seamlessly adapts to the most common operating structures like Linux, OS X, Windows, etc.

To get more details regarding the MySQL platform, visit here.

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What and When to use the Auto_Incremation?

Auto_Increment MySQL function essentially generates numeric values (sequential) whenever there is a new data entry in the MySQL Database. This automatic function operates only on numeric data types.

The sequential number that the Auto_Increment MySQL mechanism generates is used to number the columns present in the database. 

You can append the Auto_Increment mechanism to your MySQL table column by adding the AUTO_INCREMENT attribute to the CREATE TABLE statement’s column definition.

Moreover, Auto_Incrementation is a simple task and you may apply it and forget about it. However, keep in mind, that, sometime you will need to manage the AUTO_INCREMENT column especially for setting the start number or for skipping certain values.

Working of the Auto_Increment MySQL Function

Generally, to minimize redundancy, you will perform Database Normalization and store data into multiple small tables that are related to each other via Primary and Foreign Keys.

Since a primary key identifies a row in a database, it has to be unique. Now, the question is, how will you ensure that the Primary Key chosen by you is always unique? 

A feasible approach is to use a certain sequence or formula for checking the existence of a new Primary Key in the table, before adding new data. This method is complex and may result in excessive overhead. An optimal approach is to use the Auto_Increment MySQL feature to generate unique Primary Keys. 

The Auto_Increment MySQL function works with the INT (Integer) data type only. The INT data contains both signed and unsigned values. So, to keep the values positive, you can define the unsigned constraint on the Auto_Increment Primary Key.

Importance of Auto_Incremation

Auto_Increment MySQL: MySQL Database Structure
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The Auto_Increment MySQL function holds a very important stature in the MySQL Database engine due to the following reasons:

  • The Auto_Increment MySQL features automate the process of generating a unique Primary Key whenever the database table gets a new record. This way you don’t have to worry about building new Primary keys again and again for incoming records. 
  • The Auto_Increament MySQL function allows you to change the natural keys. For instance, you can ensure that a table containing names of people should have a primary key as person_id rather than last_name, first_name. This way your data will get a clear and structured representation.
  • You can enhance the read performance of your table using the Auto_Increament MySQL feature. This is because small indexes are faster to scan. However, this feature is only useful if used alongside a surrogate key. Therefore, it will help in the case of lookup tables, but not for large primary tables.
  • A sophisticated and unique naming system makes it easy for you to learn and use the database.
  • When you’re creating Data Warehouse fact tables Auto_Increament provides you with unique surrogate keys for your dimensions. This allows you to keep a very narrow fact table and provides huge capacity improvements.

Syntax of Auto_Increment MySQL Function

Auto_Increment MySQL: Syntax
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You can use the Auto_Increment MySQL function by simply using the AUTO_INCREMENT keyword after declaring the column type as shown below:

columnName columnType AUTO INCREMENT

The Auto_Increment field is declared as the primary key column and works only on the Integer data type. You can use the following syntax to use the Auto_Increment MySQL function with tables:

CREATE TABLE widgets (
    name CHAR(30) NOT NULL,
    description VARCHAR(255) NULL,
    PRIMARY KEY (id)

You should use the smallest integer data type for the AUTO_INCREMENT column that is large enough to hold the maximum sequence value you anticipate accommodating. Should the column reach the upper limit of the data type, the next attempt to generate a sequence number will fail. 

The following practices will help you in deriving the best results from the Auto_Increment MySQL feature:

  • The user-defined data type with the Auto_Increment should be able to accommodate numerous records. So, you must get familiar with the variety of INT Data Types and their limits. INTEGER, INT, SMALLINT, TINYINT, MEDIUMINT, and BIGINT are the possible data types supported by Aut_Increment. Moreover, you can include the UNSIGNED attribute to get a greater range. For instance, if you use TINYINT, the largest sequence number possible is a mere 127. However, TINYINT UNSIGNED provides you with a range of up to 255.
  • You should always ensure to specify the unsigned constraint on primary keys when using the AUTO_INCREMENT MySQL operator. This way you can avoid assigning negative numbers to any row.
  • Keep in mind that in case you delete a row from a MySQL table, its Auto_Increment id is also deleted and not re-used. Therefore, MySQL moves ahead and sequentially generates new numbers.
  • The default starting value for the AUTO_INCREMENT MySQL function is 1, and it increments by 1 for every new record.
  • You can change this according to your requirements by simply assigning the new starting value to the AUTO_INCREMENT operator. For example, using AUTO_INCREMENT = 10 will start your sequence ordering from 10.

Examples of Auto_Increment MySQL Function

Now, as you have understood the syntax of using the Auto_Increment MySQL function in the previous section, you are ready to dive into a real-time example and learn how this function can enhance your databases.

The following example adds the AUTO_INCREMENT attribute to the student_id column in a table containing student details:

CREATE TABLE students (
  first_name CHAR(30) NOT NULL,
  PRIMARY KEY (student_id)

In the above code snippet, The AUTO_INCREMENT attribute is placed next to the NOT NULL attribute. This is in alignment with the syntax provided in the previous section.

Moreover, the AUTO_INCREMENT operator only works with integer data types. Therefore, placing it next to other data types will cause the” Incorrect column specifier error” as shown below:

mysql> CREATE TABLE students (
    ->      student_id CHAR(30) NOT NULL AUTO_INCREMENT,
    ->      first_name CHAR(30) NOT NULL,
    ->      PRIMARY KEY (student_id)
    -> );

The output of the above code is as follows:

ERROR 1063 (42000): Incorrect column specifier for column 'student_id'

Now, as you will keep adding rows to the Student table using the INSERT function, the student_id column values will automatically increase. The following code will allow you to insert new rows in the student table:

INSERT INTO students (first_name) VALUE ("Rambo"); 
INSERT INTO students (first_name) VALUE ("John"); 
INSERT INTO students (first_name) VALUE ("Sam"); 

Now to view the table so far, a SELECT statement will provide the following output:

| student_id | first_name |
|           1 | Rambo     |
|           2 | John         |
|           3 | Sam          |

The above table clearly shows that the student_id value is present in an increasing sequence starting with 1 (which is the default value of the AUTO_INCREMENT MySQL operator). You can even change the initial value from 1 to any different number by using the below code:


In case you want to do this while creating a table, you can use the following code:

CREATE TABLE students (
  first_name CHAR(30) NOT NULL,
  PRIMARY KEY (student_id)

Now add some new values to the student table using the following ode:

INSERT INTO students (first_name) VALUE ("Damon"); 
INSERT INTO students (first_name) VALUE ("Anny"); 
INSERT INTO students (first_name) VALUE ("Mago"); 

The output of the above code will give a table that contains the new entries with student_id starting from 2000. This is shown below:

| student_id | first_name |
|           1 | Rambo      |
|           2 | John       |
|           3 | Sam      |
|        2000 | Damon     |
|        2001 | Anny       |
|        2002 | Margo      |

That’s it! You can go and try out the Auto_Increment MySQL function on your own.


The article introduced you to MySQL along with its unique features. It then defined the concept of the Auto_Increment MySQL function and explained its working. The article also discussed the importance and syntax of the Auto_Increment function.

Furthermore, it elaborated the use of this MySQL feature with the help of an example. After reading this article, you can also try and easily implement the Auto_Increment function for your MySQL databases.

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Share your understanding of the Auto_Increment MySQL function in the comments below!

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