erator">: </span><a href="lookup-in-read-values.html">R</a><span class="token operator">?</span></div><p class="paragraph">Checks if this column has been assigned a value retrieved from the database, then calls the <a href="lookup-in-read-values.html">found</a> block with this value as its argument, and returns its result.</p><p class="paragraph">If a column-value mapping has not been retrieved, the result of calling the <a href="lookup-in-read-values.html">notFound</a> block is returned instead.</p></div><