\begin{frame}[fragile]
  \frametitle{Queries in Databases}
  
  \begin{goal}{}
    \emph{Query:}
    the names of people living in Amsterdam.
  \end{goal}
  \medskip
  
  \begin{exampleblock}{Relational Model}
    \vspace{-1ex}
    \begin{talign}
      \{\; y \;\mid\; \myex{i}{\text{\textit{Person}}(i,y,\text{Amsterdam})} \; \}
    \end{talign}
  \end{exampleblock}
  \medskip

  \begin{exampleblock}{Tuple Model}
    \vspace{-1ex}
    \begin{talign}
      \{\; \text{Name}(x) \;\mid\; 
        &\text{\textit{Person}}(x) \wedge \text{City}(x) = \text{Amsterdam} \; \}
    \end{talign}
  \end{exampleblock}
  \medskip
  \pause
  
  \begin{exampleblock}{SQL Query}
    \begin{verbatim}SELECT Name
FROM Person
WHERE City = 'Amsterdam'\end{verbatim}
  \end{exampleblock}
\end{frame}