How to Alter Column Default Value in SQL Server

In SQL Server, altering the default value of a column is a common task when you need to modify the behavior of a database table. Default values are used to automatically fill in a column with a specific value when a new row is inserted and no value is provided for that column. This article will guide you through the steps to alter column default value in SQL Server using both T-SQL and SQL Server Management Studio (SSMS).

Using T-SQL to Alter Column Default Value

To alter the default value of a column using T-SQL, you need to execute the following SQL statement:

“`sql
ALTER TABLE table_name
ALTER COLUMN column_name column_data_type DEFAULT new_default_value;
“`

Here’s a breakdown of the syntax:

– `ALTER TABLE table_name`: Specifies the name of the table in which the column is located.
– `ALTER COLUMN column_name`: Specifies the name of the column whose default value you want to alter.
– `column_data_type`: Specifies the data type of the column. This is required even if the data type of the column is not being changed.
– `DEFAULT new_default_value`: Specifies the new default value you want to set for the column.

For example, if you have a table named `Employees` with a column `Department` of data type `VARCHAR(50)` and you want to set the default value to `’Sales’`, you would use the following T-SQL statement:

“`sql
ALTER TABLE Employees
ALTER COLUMN Department VARCHAR(50) DEFAULT ‘Sales’;
“`

Using SQL Server Management Studio (SSMS) to Alter Column Default Value

If you prefer to use SSMS, follow these steps:

1. Open SSMS and connect to your SQL Server instance.
2. In the Object Explorer, expand the server, expand the database, and then expand the table where you want to alter the default value.
3. Right-click on the column whose default value you want to alter and select “Design” from the context menu.
4. In the table design view, click on the “Default” cell next to the column you want to modify.
5. Enter the new default value in the “Default Value or Expression” box.
6. Click “Save” to apply the changes.

By following these steps, you can successfully alter the default value of a column in SQL Server using either T-SQL or SSMS. Remember to back up your database before making any changes to ensure data integrity.