\begin{frame}
  \frametitle{Unnecessary Joins}
  
  \tableExercisesResults
  \bigskip

  \begin{quiz}{\textwidth}{What will be the result of this query?}
    \small
    \BUseVerbatim{xproduct}
  \end{quiz}
  %% Note: cross product between Results and Exercises
\end{frame}