def dataset(db=nil)
      db ||= self.class.default_db
      builder = Database::DatasetBuilder.new(db, self)
      builder.select(@columns)
      builder.filter(@filters)
      builder.order(@order)
      builder.limit(@limit) if @limit
      builder.dataset
    end
def dataset(db=nil)
      db ||= self.class.default_db
      builder = Database::DatasetBuilder.new(db, self)
      builder.select(@columns)
      builder.filter(@filters)
      builder.order(@order)
      builder.limit(@limit) if @limit
      builder.dataset
    end
Applies the query to a Sequel::Database and returns a
 Sequel::Dataset.

 @api public