    # File lib/active_record/connection_adapters/sqlserver_adapter.rb, line 477
          def remove_default_constraint(table_name, column_name)
            constraints = select "select def.name from sysobjects def, syscolumns col, sysobjects tab where col.cdefault = def.id and col.name = '#{column_name}' and tab.name = '#{table_name}' and col.id = tab.id"

            constraints.each do |constraint|
              execute "ALTER TABLE #{table_name} DROP CONSTRAINT #{constraint["name"]}"
            end
          end