\begin{frame}
  \frametitle{Entity-Relationship Model}
  
  \entityexample
    
  \begin{itemize}
    \item \emph{Rectangles} \;\scalebox{.7}{\tikz[baseline=-.75ex] \node[entity] {\quad};}\; 
          represent entity sets
    \item \emph{Ellipses} \;\scalebox{.8}{\tikz[baseline=-.75ex] \node[attribute] {\vphantom{A}\quad};}\; 
          represent attributes
      \begin{itemize}
        \item \emph{Double ellipses} \;\scalebox{.8}{\tikz[baseline=-.75ex] \node[multi attribute] {\vphantom{A}\quad};}\;
              represent multi-valued attributes
        \item \emph{Dashed ellipses} \;\scalebox{.8}{\tikz[baseline=-.75ex] \node[derived attribute] {\vphantom{A}\quad};}\;
              denote derived attributes
      \end{itemize}
    \item \emph{Diamonds} \;\;\scalebox{.8}{\tikz[baseline=-.75ex] \node[relationship,minimum size=8mm] {};}\; 
          represent relationship sets
    \item \emph{Lines} link attributes and relationship sets to entity sets
    \item \emph{Underline} indicates primary key attributes
  \end{itemize}
  \vspace{10cm}
\end{frame}