# File lib/dbi/dbi.rb, line 330
  def to_s
    s = sprintf("%04d-%02d-%02d %02d:%02d:%02d", @year, @month, @day, @hour, @minute, @second) 
    if @fraction.nil?
      s
    else
      s + '.' + @fraction.to_s.split('.').last
    end
  end