I get the following error when trying to query a SQL Server datasource with a column type of nvarchar:

undefined method []' for nil:NilClass /path/to/ruby/gems/rdbi-driver-odbc-0.1.2/lib/rdbi/driver/odbc.rb:214:inblock in new_execution'

I was able to get past the error by editing lines 214 and 215 in odbc.rb to include rescue nil and rescue :default, respectively, but obviously I'm not submitting that as a pull request since that's probably the most ham-fisted approach one could have come up with to address the issue.