\begin{frame} \frametitle{Differences: ER Models vs. UML Class Diagrams} \begin{itemize} \item visual differences --- no big deal \medskip \item \emph{keys}: \begin{itemize} \item ER supports keys (underlining) \item UML has no standard for indicating keys\\ \remark{Some people underline, others write \textit{PK} after the attribute.} \end{itemize} % \pause % \begin{exampleblock}{} % \begin{minipage}{.4\textwidth} % In case of composition in UML, one may use \emph{association qualifiers} to indicate the key. % \end{minipage}~\quad~% % \begin{minipage}{.49\textwidth} % \begin{center} % \scalebox{.8}{ % \begin{tikzpicture} % \umlclass{book}{ % +ISBN \\ % +title \\ % +author % }{ % } % \umlclass[x=5]{section}{ % +nr \\ % +title % }{ % } % \node [rectangle,draw,fill=yellow!20,anchor=west] at (book.east) (isbn) {ISBN}; % \umlcompo[arg1=$1..1$,mult2=$\,$,arg2=$0..*$,mult2=$\,$,pos2=0.8]{isbn}{section} % \end{tikzpicture} \vspace{-2ex} % } % \end{center} % \end{minipage} % \end{exampleblock} \medskip \item \emph{aggregation}: means something very different \begin{itemize} \item in ER: treating a relationship set as an entity \item in UML: a part-whole relation\\(non-exclusive form of composition) \end{itemize} \medskip \item \emph{weak entities}: \begin{itemize} \item in ER: weak entities are entities without own key \item in UML: composition is similar, but says nothing about keys \end{itemize} \end{itemize} \end{frame}