Add a column in SQL Server

In SQL Server, you can add a new column to an existing table using the ALTER TABLE statement.

 Syntax:

ALTER TABLE table_name
ADD column_name data_type [NULL | NOT NULL] [DEFAULT default_value];

 Example 1: Add a simple column

ALTER TABLE Employees
ADD Department VARCHAR(50);

 This adds a new column called Department to the Employees table.

 Example 2: Add a column with a default value

ALTER TABLE Employees
ADD IsActive BIT NOT NULL DEFAULT 1;

 Adds a column IsActive that:

• Has data type BIT (boolean),

• Cannot be NULL,

• Defaults to 1 (true) for all existing rows.

 Example 3: Add multiple columns at once

ALTER TABLE Employees
ADD JoiningDate DATE,
    Salary DECIMAL(10, 2);

 Adds two columns JoiningDate and Salary to the table.

 Notes:

• Adding a NOT NULL column without a default value will fail if the table already contains data.

• If you add a DEFAULT constraint, existing rows will automatically get the default value.

If you want to add a new column in SQL Server, you can use the ALTER TABLE statement.

Syntax:

ALTER TABLE table_name
ADD column_name datatype [NULL | NOT NULL] [DEFAULT default_value];

Example 1: Add a nullable column

ALTER TABLE Employees 
ADD MiddleName VARCHAR(50) NULL;

• This will add a column MiddleName of type VARCHAR(50) that can contain NULL.

Example 2: Add a NOT NULL column with default value

ALTER TABLE Employees 
ADD CreatedDate DATETIME NOT NULL DEFAULT GETDATE();

• This will add a CreatedDate column with default current date/time for existing and new rows.

Example 3: Add multiple columns

ALTER TABLE Employees 
ADD DepartmentID INT NULL, 
    Salary       DECIMAL(10,2) NULL;

• Notes:

• If table already has rows, adding a NOT NULL column requires a DEFAULT value.

• Always check dependencies (views, stored procedures) before altering a table in production.

Hi Kiran Kumar,

You can add a column to an existing table in SQL Server, using the ALTER TABLE statement. 

Syntax:

ALTER TABLE table_name
ADD column_name data_type [NULL | NOT NULL] [DEFAULT default_value];

Example:

Suppose you have a table Employees and you want to add a column named DateOfBirth of type DATE which allows null values:

ALTER TABLE Employees
ADD DateOfBirth DATE NULL;

Hope this will help you!