如何在遇到的最后一个单词后用点替换最后一个逗号？

Question

我的问题是有关的但有些复杂。如何用最后一个逗号替换最后一个逗号遭遇单词？

% !TeX program = pdflatex                                   
% !TeX encoding = utf8


\documentclass[]{book}
\usepackage{filecontents}
\begin{filecontents*}{data.dat}
Number|Entry
1|Alpha
2|Beta
2|Gamma
3|Delta
\end{filecontents*}

\usepackage{datatool}
\DTLsetseparator{|}
\DTLloaddb{letters}{data.dat}

\begin{document}

\DTLforeach*[\Number=2]{letters}% database label
{\Number=Number, \Entry=Entry}% assignment
{% Stuff to do at each iteration:
            \DTLiflastrow{\Entry.}{\Entry,} % Here should be a right solution
}
\end{document}

Answer 1

反过来：

\documentclass[]{book}
\usepackage{filecontents}
\begin{filecontents*}{data.dat}
Number|Entry
1|Alpha
2|Beta
2|Gamma
3|Delta
\end{filecontents*}

\usepackage{datatool}
\DTLsetseparator{|}
\DTLloaddb{letters}{data.dat}

\begin{document}

\DTLforeach*[\Number=2]{letters}% database label
{\Number=Number, \Entry=Entry}% assignment
{\DTLiffirstrow{}{, }%
% Stuff to do at each iteration:
\Entry
}
\end{document}