Rename column SQL Server 2008

Use sp_rename

EXEC sp_RENAME 'TableName.OldColumnName' , 'NewColumnName', 'COLUMN'

See: SQL SERVER – How to Rename a Column Name or Table Name

Documentation: sp_rename (Transact-SQL)

For your case it would be:

EXEC sp_RENAME 'table_name.old_name', 'new_name', 'COLUMN'

Remember to use single quotes to enclose your values.

Alternatively to SQL, you can do this in Microsoft SQL Server Management Studio. Here are a few quick ways using the GUI:

First Way

Slow double-click on the column. The column name will become an editable text box.

Second Way

Right click on column and choose Rename from the context menu.

For example:

Third Way

This way is preferable for when you need to rename multiple columns in one go.

1. Right-click on the table that contains the column that needs renaming.
2. Click Design.
3. In the table design panel, click and edit the textbox of the column name you want to alter.

For example:

_{NOTE: I know OP specifically asked for SQL solution, thought this might help others :)}