SQL Server Auto Increment

Welcome Dev, in this article, we will discuss SQL Server Auto Increment. If you are a developer who needs to generate unique identifiers for your database records, you will find this feature useful. SQL Server provides an auto-increment feature that allows you to generate unique numbers for a column automatically. Let us dive deep into this feature to know more about it.

What is Auto Increment in SQL Server?

Auto increment is a feature in SQL Server that automatically generates unique values for a column. This is useful when you need to create primary keys for your table or any column that requires unique values. When you set a column as an auto-increment column, SQL Server automatically generates a new value every time a new row is inserted into the table.

Let us take an example:

ID	Name	Email
1	John	john@example.com
2	Jane	jane@example.com
3	David	david@example.com

In the above example, the column ‘ID’ is an auto-increment column. SQL Server automatically generates a new value every time a new row is inserted into the table. As you can see, the values in the ‘ID’ column are unique and consecutive.

How to Create Auto Increment Column in SQL Server?

To create an auto-increment column in SQL Server, you need to set the ‘Identity’ property of the column. Setting this property enables SQL Server to generate a new value every time a new row is inserted into the table. Here is how you can create an auto-increment column:

Step 1: Create a Table

The first step is to create a table with the column you want to make auto-increment.

CREATE TABLE users (ID INT PRIMARY KEY,Name VARCHAR(50),Email VARCHAR(50));

Step 2: Set Identity Property

The next step is to set the ‘Identity’ property of the column. Here is how you can do it:

ALTER TABLE usersALTER COLUMN ID INT IDENTITY (1,1);

The above query sets the ‘ID’ column as an auto-increment column. The first parameter of the ‘IDENTITY’ function represents the starting value, and the second parameter represents the increment value. In this case, the starting value is 1, and the increment value is 1.

FAQs

Q. Can we make any column auto-increment in SQL Server?

A. No, we can only set integer columns as auto-increment columns in SQL Server.

Q. What happens if we insert a value into an auto-increment column?

A. If we insert a value into an auto-increment column explicitly, SQL Server will use that value as the starting value for the next auto-increment value.

Q. Can we reset the auto-increment value in SQL Server?

A. Yes, we can reset the auto-increment value in SQL Server by truncating the table or using the ‘DBCC CHECKIDENT’ command.

Q. What is the maximum value an auto-increment column can generate?

A. In SQL Server, the maximum value an auto-increment column can generate is 2,147,483,647. If you reach this value, the next value generated will be the negative number -2,147,483,648.

Conclusion

In conclusion, auto-increment is a useful feature in SQL Server that allows you to generate unique values for a column automatically. By setting the ‘Identity’ property of a column, you can enable this feature and let SQL Server handle the generation of unique values. We hope that this article helps you in understanding the auto-increment feature in SQL Server. Happy learning!