\begin{frame} \frametitle{Having} \begin{alertblock}{} Aggregations may not be used in the \sql{where} clause. \end{alertblock} \medskip With \sql{group by}, however, it makes sense to \emph{filter out entire groups} based on some aggregated group property. \pause \begin{goal}{} This is possible with SQL's \sql{having} clause. \end{goal} \begin{code}{\textwidth}{} For example, only groups of size greater than $n$ tuples. \medskip \small \BUseVerbatim{query} \end{code} \begin{alertblock}{} The condition in the \sql{having} clause may (only) involve aggregation functions. % and the \sql{group by} attributes. \end{alertblock} \end{frame}