title: Index varchar on MS SQL Server 2005
body: <p>I need to index a varchar field on my table in MS SQL Server 2005, but it's not clear to me how to do so.  If I try to add a non-clustered index on the field, it says "Column 'xxxx' in table 'mytable' is of a type that is invalid for use as a key column in an index"</p>
  
  <p>My table has an auto-increment int ID that is set as the primary key on the table.  If I set this property as the index, and then add my varchar column as an "included column", the index goes through.  But I'm not sure that's what I want - I want to be able to search the table based on the varchar field alone, and my understanding of indexes was that all indexed elements had to be provided to actually see a speedup in the query, but I don't want to have to included the int ID (because I don't know what it is, at the time of this given query).</p>
  
  <p>Am I trying to do this incorrectly? Would the ID + my varchar as an included column accomplish what I am looking for?</p>