How to write SQL Statements With Spaces In Column Names
You can use ` try with:

$query = \Drupal::database()-&gt;select('Product_Details', 'n');
$query-&gt;addField('n', 'S.No.');
$query-&gt;condition('n.`Product type`', 'Irons');
$results = $query-&gt;execute()-&gt;fetchAll();


According to this post https://stackoverflow.com/questions/14190798/how-to-select-a-column-name-with-a-space-in-mysql you can use also [].