SQL Server ADD COLUMN Tutorial

Table of contents

Add a single column

Syntax

ALTER TABLE table_name ADD column_name data_type;
  • table_name - The name of the table you want to alter.
  • column_name - The name of the column you want to add to the table.
  • data_type - A supported data type.

Example

The following command adds a column building_name to the rent_payments table.

ALTER TABLE rent_payments ADD building_name VARCHAR(10);

Add multiple columns

To add multiple columns, just list the columns inside parentheses as follows.

ALTER TABLE
    table_name
ADD
    first_column data_type,
    second_column data_type;

Example

The following command adds two columns to the rent_payments table.

ALTER TABLE
    rent_payments
ADD
    building_name varchar(10),
    unit_number int;

Column constraints

Add any column constraints after the column data type as follows.

ALTER TABLE table_name ADD column_name constraints;

Example

The following command creates a column payment_id with a PRIMARY KEY constraint.

ALTER TABLE rent_payments ADD payment_id INT PRIMARY KEY;