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\begin{frame}
  \frametitle{Relational Model}

  \begin{block}{}
    \emph{Instance:} actual content (`state') of the database at some moment
  \end{block}  
  \pause

  \begin{exampleblock}{Example Relational Database Instance}
    \scalebox{.8}{
    \begin{tabular}{| c | c | c | c |}
    \rowcolor{mblue!20}
    \mc{4}{customer} 
    \\ \hline \rowcolor{mblue!40}
    \ul{id}  & name & street & city 
    \\ \hline \rowcolor{mblue!20}
    192837465 & Johnson & 12 Alma & Palo Alto 
    \\ \hline \rowcolor{mblue!20}
    019283746 & Smith & 4 North & Rye 
    \\ \hline \rowcolor{mblue!20}
    192837465 & Johnson & 3 Alma & Palo Alto
    \\ \hline \rowcolor{mred!30}
    \anchor{relational-row} 321123123 & Jones & 34 Main & Harisson 
    \\ \hline \rowcolor{mblue!20}
    019283746 & Smith & 7 South & Rye 
    \\ \hline 
    \end{tabular}
    }
    \hfill%
    \scalebox{.8}{
    \begin{tabular}{|c|c|}
    \rowcolor{mblue!20}
    \mc{2}{account} 
    \\ \hline \rowcolor{mblue!40}
    depositor  & \ul{accountnr} 
    \\ \hline \rowcolor{mblue!20}
    19283465 & 101343
    \\ \hline \rowcolor{mblue!20}
    019283746 & 215569
    \\ \hline \rowcolor{mblue!20}
    192837465 & 201541
    \\ \hline \rowcolor{mblue!20}
    321123123 & 217343
    \\ \hline \rowcolor{mblue!20}
    019283746 & 201762
    \\ \hline 
    \end{tabular}
    }
    \medskip
    \begin{itemize}
      \item \anchor{relational-from}tuple record (row)
      %\item sequence of columns/attributes
    \end{itemize}
    \begin{tikzpicture}[remember picture,overlay]
      \draw [very thick,->,dblue] ($(relational-from)+(-4mm,0mm)$) -- ($(relational-from)+(-7.2mm,0mm)$) to[out=180,in=180,looseness=1.5] ($(relational-row)+(-2.7mm,1.5mm)$);
    \end{tikzpicture}\vspace{-2ex}%
  \end{exampleblock}
  \pause

  In the \emph{pure relational model}, a table is a \emph{set} of tuples:%
  \begin{itemize}
    \item has no duplicate tuples (rows)
    \item no order on the tuples
  \end{itemize}  
\end{frame}