How do I apply an OR condition? I've got the below code

$query = \Drupal::database()
  -&gt;select("excel", "e")-&gt;fields("e");
$group = $query-&gt;orConditionGroup()
  -&gt;condition("grupindex", 1)
  -&gt;condition("grupkodu", NULL);
$query-&gt;condition($group);
$excel_products = $query-&gt;execute()-&gt;fetchAll();


When I run SELECT * FROM excel WHERE grupkodu = 1 OR grupkodu IS NULL, I get 1594 records, however the above code gives only 638 records, which means only grupkodu condition is taken into account. What is the proper way to apply OR?
After a bit of dabbling, I got the answer. -&gt;condition("grupkodu", NULL); is not sufficient, it needs to be -&gt;condition("grupkodu", NULL, "IS NULL");