title: SQL Server - script to update database columns from varchar to nvarchar if not already nvarchar
body: <p>I am in a situation where I must update an existing database structure from varchar to nvarchar using a script.  Since this script is run everytime a configuration application is run, I would rather determine if a column has already been changed to nvarchar and not perform an alter on the table.  The databases which I must support are SQL Server 2000, 2005 and 2008.  </p>