How to Alter Table for Identity Column in SQL Server
In SQL Server, the identity column is a feature that automatically generates unique values for each row inserted into a table. It is commonly used for primary keys and other columns that require unique identifiers. However, there may be situations where you need to alter the table to modify the identity column. This article will guide you through the process of altering a table for an identity column in SQL Server.
Understanding the Identity Column
Before diving into the alteration process, it is essential to understand the basics of the identity column. An identity column is defined using the IDENTITY keyword in SQL Server. It is typically used in conjunction with the PRIMARY KEY constraint to ensure that each row has a unique identifier. The identity column can be configured with various properties, such as the seed value, increment value, and maximum value.
Step-by-Step Guide to Altering a Table for an Identity Column
To alter a table for an identity column in SQL Server, follow these steps:
1. Open SQL Server Management Studio (SSMS) and connect to your database.
2. In the Object Explorer, navigate to the database where the table resides.
3. Right-click on the table and select “Design” to open the table in Design view.
4. In the table design, locate the identity column you want to alter.
5. Right-click on the identity column and select “Properties” to open the Properties window.
6. In the Properties window, you will find various properties related to the identity column, such as “Identity Specification,” “Seed,” and “Increment.”
7. Modify the desired properties according to your requirements. For example, if you want to change the seed value, locate the “Seed” property and enter the new value.
8. Save the changes by clicking “Save” in the Design view or by closing the table design and accepting the changes.
Example: Altering an Identity Column
Let’s consider an example where we have a table named “Employees” with an identity column named “EmployeeID.” We want to change the seed value of the identity column to 1000.
1. Open SSMS and connect to your database.
2. Navigate to the “Employees” table in the Object Explorer.
3. Right-click on the “Employees” table and select “Design.”
4. In the table design, locate the “EmployeeID” column.
5. Right-click on the “EmployeeID” column and select “Properties.”
6. In the Properties window, locate the “Seed” property and enter “1000.”
7. Save the changes by clicking “Save” in the Design view or by closing the table design and accepting the changes.
Conclusion
Altering a table for an identity column in SQL Server is a straightforward process. By following the steps outlined in this article, you can easily modify the properties of an identity column, such as the seed value and increment value. Remember to save your changes and test the alterations to ensure they meet your requirements.
