\begin{frame}
  \frametitle{Relation Schema}

  \begin{block}{Relation schema}
    A \textbf{relation schema} $s$ (of a single relation)
    defines

    \begin{itemize}
    \item a (finite) sequence $A_1, \dots, A_n$ of distinct \textbf{attribute names},
    \smallskip
    
    \item for each attribute $A_i$ a \emph{data type} (or \textbf{domain}) $D_i$.
    \end{itemize}
    A relation schema can be written as 
    \begin{talign}
      s = (A_1:D_1, \dots, A_n:D_n)
    \end{talign}
  \end{block}
  %Let $\var{dom}(A_i) = \dom{D_i}$ be the set of possible values for $A_i$.
  \smallskip
    
  \structureExercises
  
  \begin{code}{1\textwidth}{Creating a relation schema in SQL}
  \small
  \BUseVerbatim{createtable}
  \end{code}
\end{frame}