\begin{frame}
  \frametitle{Conditional Expressions}
  
  \begin{goal}{}
    ``Union'' is the \emph{portable way} to conduct a case analysis.\\[1ex]
    Sometimes a \emph{conditional expression} suffices \& more efficient.
  \end{goal}
  \remark{%
    Conditional expression syntax varies between DBMSs.\\
    Oracle uses $\sql{decode(}\cdots\sql{)}$, for example.
  }
  \pause\medskip
    
  Here, we will use the SQL-92 syntax.
  \medskip
  
  \begin{code}{\textwidth}{Assigning student grades based on homework 1}
    \small
    \BUseVerbatim{query}
  \end{code}
\end{frame}