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SQL Server - ALTER COLUMN Keyword



The SQL Server (Transact-SQL) ALTER COLUMN keyword is used to change the data type of a column in an existing table.

Syntax

The syntax for using ALTER COLUMN statement to modify datatype of a column in SQL Server (Transact-SQL) is given below:

ALTER TABLE table_name
ALTER COLUMN column_name datatype;

Example:

Consider a database table called Employee with the following records:

EmpIDNameCityAge
1JohnLondon25
2MarryNew York24
3JoParis27
4KimAmsterdam30

In this table, the datatype of City column is VARCHAR(100). To change the datatype of the column to VARCHAR(255), the SQL Server code is given below:

ALTER TABLE Employee
ALTER COLUMN City VARCHAR(255);

This will change the datatype of City column from VARCHAR(100) to VARCHAR(255). For a complete reference of all the data types available in SQL Server database, see Data Types reference.


❮ SQL Server Keywords

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