documentclass{article}
usepackage{pgfplotstable}
usepackage{pgfplots}
pagestyle{empty}
begin{document}

%pgfplotstabletypeset{data.dat}

vspace{1cm}

begin{tikzpicture}
begin{axis}[
  xlabel=Q Series,
  ylabel=P Values]
addplot table [y=P, x=$Q_A$]{data.dat};
addlegendentry{$Q_A$ series}
addplot table [y=P, x=$Q_B$]{data.dat};
addlegendentry{$Q_B$ series}
addplot table [y=P, x=$Q_D$]{data.dat};
addlegendentry{$Q_D$ series}
end{axis}
end{tikzpicture}

end{document}

P $Q_A$ $Q_B$ $Q_D$
10 5 7 12
8 8 10 18
6 12 16 28