Varchar to date in SQL Server 2008
This is string manipulation: nothing to do with datetimes

SELECT
   SUBSTRING(Whatever, 4,2) + '-' + LEFT(Whatever, 2) + '-' + RIGHT(Whatever, 4)
FROM
   SomeTable;


If you stored it as datetime, then you'd format it into whatever locale you wanted on the client. Then it'd be sortable and comparable too.