SQL Server ADD COLUMN Tutorial
Table of contents
- Add single column - Add a single column to a table.
- Add multiple columns - Add multiple columns to a table.
- Column constraints - Add constraints like
PRIMARY KEYorUNIQUEto a column.
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;