How to: Modify Column Data Types
You can modify the data type of a column in Table Designer.
Note
A new version of Table Designer appears for databases in the SQL Server 2012 format. This topic describes the old version of Table Designer, which you use with databases in earlier formats of SQL Server.
In the new version, you can change a table definition through a graphical interface or directly in a script pane. If you use the graphical interface, the table’s definition is automatically updated in the script pane. To apply the SQL code in the script pane, choose the Update button. For more information about the new version, see How to: Create Database Objects Using Table Designer.
Warning
Modifying the data type of a column that already contains data can result in the permanent loss of data when the existing data is converted to the new type. In addition, code and applications that depend on the modified column may fail. These include queries, views, stored procedures, user-defined functions, and client applications. Note that these failures will cascade. For example, a stored procedure that calls a user-defined function that depends on the modified column may fail. Carefully consider any changes you want to make to a column before making it.
Note
Your computer might show different names or locations for some of the Visual Studio user interface elements in the following instructions. The Visual Studio edition that you have and the settings that you use determine these elements. For more information, see Customizing Development Settings in Visual Studio.
To modify the data type of a column
In Server Explorer, right-click the table with columns you want to modify and click Open Table Definition.
The table opens in Table Designer.
Select the column for which you want to modify the data type.
In the Column Properties tab, click the grid cell for the Data Type property and choose a new data type from the drop-down list.
The new data type is assigned to the column after you click outside the grid cell or use the TAB key to move to another grid cell. It takes effect in the database when you save your changes in Table Designer.
Note
When you modify the data type of a column, Table Designer applies the default length of the data type you selected, even if you have already specified another. Always set the data type length for to the desired value after specifying the data type.