\begin{frame}[t] \frametitle{Exercise} \structureAll \medskip \begin{quiz}{0.95\textwidth}{Formulate the following query in SQL} The topics of all exercises solved by George Orwell? \end{quiz} \bigskip The \emph{connection graph} with foreign key relations: \begin{center} \begin{tikzpicture}[n/.style={rectangle,rounded corners=1mm,draw=black,fill=cblue!30,inner sep=1mm}] \node (S) [n] {\sql{Students}}; \node (R) [n,right of=S,node distance=35mm] {\sql{Results}}; \node (E) [n,right of=R,node distance=35mm] {\sql{Exercises}}; \draw (S) to node [below,align=center] {} (R); \draw (R) to node [below,align=center] {} (E); \end{tikzpicture}\vspace{-1ex} \end{center} \pause We establish the link via a tuple variable \sql{R} over \sql{Results}: \begin{tcenter} \begin{code}{\textwidth}{} \small \BUseVerbatim{query} \end{code} \end{tcenter} \end{frame}