\begin{frame}
  \frametitle{Not In}

  \structureExercisesResults
  \smallskip

  \begin{code}{\textwidth}{Topics of homework tasks solved by at least one student}
    \pause
    \small
    \BUseVerbatim{query}%
  \end{code}
  \pause\vspace{-1ex}
  
  \begin{quiz}{\textwidth}{Is there a difference to this query?\\ (with or without
      \sql{distinct})}
    \small
    \BUseVerbatim{semi}
  \end{quiz}

  % with distinct: first one yields duplicates if there are multiple Exercises with the same topic
  % without distinct: second one yields duplicates for every result  
\end{frame}