title: Oracle - Select statement throwing an error
body: <p>Please check out this link.</p>
  
  <p>You can see the error message:</p>
  
  <p><a href="https://i.stack.imgur.com/iNPVl.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/iNPVl.png" alt="enter image description here"></a></p>
  
  <p>Note : I intentionally kept <code>roll_no</code> as a character type.
  I need help with the select statement.</p>
  
  <p>Thanks</p>