Fix paginate_by_sql for MSSQL adapter

[denniskis]

paginate_by_sql adds LIMIT option which is not working with MSSQL.

[viegasfh]

Same holds true for Firebird SQL. I modifed active_record.rb as follows:

      oracle = self.connection.adapter_name =~ /^(oracle|oci$)/i
      firebird = self.connection.adapter_name == 'Rubyfb'

      # add limit, offset
      if oracle
        query = <<-SQL
          SELECT * FROM (
            SELECT rownum rnum, a.* FROM (#{query}) a
            WHERE rownum <= #{pager.offset + pager.per_page}
          ) WHERE rnum >= #{pager.offset}
        SQL
      elsif firebird
        query << " ROWS #{pager.offset+1} TO #{pager.per_page+pager.offset}"
      else
        query << " LIMIT #{pager.per_page} OFFSET #{pager.offset}"
      end

This will work with Rubyfb driver or Firebird, and it only supports Firebird 2.0+

[tflanitzer]

The problem reported by denniskis still exists after 2 years. Merging this into a near future release would be highly appreciated.