span class="token operator">?</span></span></span><span class="token punctuation">)</span><span class="token operator">: </span><a href="../-entity/lookup-in-read-values.html">R</a><span class="token operator">?</span></div><div class="brief "><p class="paragraph">Checks if this column has been assigned a value retrieved from the database, then calls the <a href="../-entity/lookup-in-read-values.html">found</a> block with this value as its argument, and returns its result.</p></div></div></div>
            