title: If-else Statement with drop-down list
body: <p>I am doing a Sign Up page. So, there is a drop-down list where users are to choose whether they are a student, staff or guest. If Student is chosen, they need to key in their Admin Number. For Staffs, Staff ID and for Guest its NRIC.</p>
  
  <p>May I know how to do so? </p>
  
  <p><img src="https://i.stack.imgur.com/9RSOK.png" alt="enter image description here"></p>