\begin{frame}
  \frametitle{Splitting Relations: Unnecessary Splits}

  \begin{alertblock}{}
  Not every lossless split is reasonable!
  \end{alertblock}

  \begin{exampleblock}{}
    \begin{center}
      {\ttfamily\footnotesize
    \colorbox{rellight}{%
      \begin{tabular}{|r|r|r|}
        \multicolumn{3}{c}{Students} 
        \\
        \hline
        \hd{\underline{sid}} & \hd{first} & \hd{last} \\
        \hline
        101 & George & Orwell \\ 
        102 & Elvis & Presley \\ 
        \hline
      \end{tabular}%
      }}
    \end{center}
    \pause
    Splitting \sql{Students} into
    \begin{center}
      \sql{StudentsFirst(\underline{sid}, first)}\\
      \sql{StudentsLast(\underline{sid}, last)}
    \end{center}
    is lossless\pause, but
    \begin{itemize}
      \item the split is \emph{not} necessary to enforce a normal form, and
      \item only requires costly joins in subsequent queries. 
    \end{itemize}
  \end{exampleblock}
\end{frame}