\documentclass{article}

\usepackage{datatool}

\begin{filecontents*}{xx.csv}
2014.02.26
2014.11.12.tm
mm
\end{filecontents*}

\begin{document}

\DTLloaddb[noheader,keys={RowID}]{newbDB}{xx.csv}

\DTLforeach*{newbDB}{\RowID=RowID}%
{%
   \DTLifSubString{2014.02.26,26,2014.11.12.tm}{\RowID}{}{}%
}%

\end{document}
