\begin{frame} \frametitle{Introduction} \begin{goal}{} If a ``good'' ER schema is transformed into the relational model, the result will \emph{satisfy all normal forms} (4NF, BCNF, 3NF). \end{goal} A normal form violation detected in the generated relational schema indicates a \emph{flaw} in the input ER design. \\[2ex] This needs to be corrected on the ER level. \smallskip \pause \begin{exampleblock}{FDs in the ER model} The ER equivalent of the very first example in this chapter: \smallskip \begin{minipage}{.32\textwidth} \scalebox{.9}{ \begin{tikzpicture}[every edge/.style={link}] \node[entity] (customer) {Courses}; \node[attribute] [above left of=customer,node distance=1.7cm,shift={(-5mm,-3mm)}] {\key{courseNr}} edge (customer); \node[attribute] [above of=customer,node distance=1.3cm] {title} edge (customer); \node[attribute] [left of=customer,node distance=2.1cm,yshift=-1mm] {phone} edge (customer); \node[attribute] [below left of=customer,node distance=1.5cm] {instructor} edge (customer); \end{tikzpicture} } \end{minipage} \begin{minipage}{.67\textwidth} \begin{itemize} \pause \item The FD $\text{instructor} \to \text{phone}$ leads to a violation of BCNF in the resulting table for entity Courses. \pause \item \alert{Also in the ER model, FDs between attributes of an entity set should be implied by a key constraint.} \end{itemize} \end{minipage} \end{exampleblock} \end{frame}