\begin{frame}
  \frametitle{Not In}

  \begin{code}{\textwidth}{}
    \small
    \BUseVerbatim{query}
  \end{code}

  \begin{goal}{Conceptually \ldots}
    The \emph{subquery} is evaluated before the \emph{main query}:\\[1ex]
    {\small
    \begin{minipage}{.65\textwidth}
      \begin{tcenter}
      \tableStudents
      \end{tcenter}
    \end{minipage}
    \begin{minipage}{.34\textwidth}
      \begin{tcenter}\tableSqeeze
      \colorbox{rellight}{%
        \begin{tabular}[t]{|r|}
          \multicolumn{1}{c}{Subquery result} \\ \hline
          \hd{sid} \\ \hline
          101 \\ 
          102 \\ 
          103 \\ 
          \hline
        \end{tabular}%
      }%
      \end{tcenter}
    \end{minipage}
    }
    \smallskip
    
    Then, for every tuple of \sql{Students}, a matching \sql{sid} is
    searched in the subquery result.  If there is none, the tuple is output.
  \end{goal}
\end{frame}