Randomly Selecting Problems Not Used in the Past Two Years

This example requires mth101.dbtex. If you use make, there's also a Makefile. If you don't use make, the file problems.dbtex can be created using:

datatooltk --in mth101.dbtex --merge Label mth101-years.dbtex --shuffle --filter-and --filter Year ne 2012 --filter Year ne 2013 --truncate 5 --output problems.dbtex

This file needs to be created before building the document. The years should be changed as appropriate if the current year is no longer 2014.

\documentclass{article}

\usepackage{etoolbox}
\usepackage{datatool}

\newbool{showanswers}
\booltrue{showanswers}

\DTLloaddbtex{\problemDB}{mth101.dbtex}

\InputIfFileExists{mth101-years.dbtex}
{}% file exists
{\DTLnewdb{mth101-years}}% file doesn't exist

\begin{document}
\begin{center}\bfseries\Large
Assignment~1\ifbool{showanswers}{ (Solution Sheet)}{}
\end{center}

\dtlexpandnewvalue
\begin{enumerate}
\DTLforeach*{\problemDB}
 {\Label=Label,\Question=Question,\Answer=Answer}%
 {%
   \item \Question
   % add this label to the new database:
   \DTLnewrow{mth101-years}% add new row
   \DTLnewdbentry{mth101-years}{Label}{\Label}%
   \DTLnewdbentry{mth101-years}{Year}{\number\year}%
   \ifbool{showanswers}{\par\textbf{Solution: }\Answer}{}%
 }
\end{enumerate}

\DTLsaverawdb{mth101-years}{mth101-years.dbtex}
\end{document}

Download assignmentsheet1.tex or assignmentsheet1.pdf.