 class="st"> </span><span class="ot">NULL</span>]</span></code></pre></div>
<p>is equivalent to the code above.</p></li>
</ul>
</div>
</div>
<div id="ref-j-by" class="section level3">
<h3>d) <code>:=</code> along with grouping using <code>by</code></h3>
<p>We have already seen the use of <code>i</code> along with <code>:=</code> in <a href="#ref-i-j">Section 2b</a>. Let’s now see how we can use <code>:=</code> along with <code>by</code>.</p>
<div id="how-can-we-add-a-new-column-which-contains-for-each-ori