\begin{frame}
  \frametitle{ANSI SPARC Architecture: 3 levels}

  \begin{block}{ANSI SPARC Architecture}
  \begin{itemize}
  \smallskip
    \item \emph{View level:} 
      \begin{itemize}
        \item application programs hide details of data types
        \item hide information (e.g. exam grade) for privacy or security
      \end{itemize}
  \medskip
    \item \emph{Logical level:} also called `conceptual schema'
      \begin{itemize}
        \item describes data stored in the database, and
        \item relations among the data
      \end{itemize} 
  \medskip
    \item \emph{Physical level:} 
      \begin{itemize}
        \item how the data is stored
        \item disk pages, index structures, byte layout, record order
      \end{itemize}
  \smallskip
  \end{itemize}  
  \end{block}
  \pause\bigskip
  
  This ensures logical and physical data independence\ldots
\end{frame}