title: Relative select field
body: <p>I have two tables </p>
  
  <p><code>NIC (nic_id,nic_no,name,address)</code>
  and </p>
  
  <p><code>License (license_id,license_no,type,expiry_date)</code>.</p>
  
  <p>I am using <code>cnic_id</code> as foreign key in license table.</p>
  
  <p>On the license page there are fields that are displaying License ID,License NO, NIC NO(Select box),License type, Expiry Date.
  Nic no are from nic table displaying nic no's.</p>
  
  <p>I want a license_no to be assigned to a unique nic_no, so that one license no has only one nic_no.</p>
  
  <p>The system does not allow assignment of two nic no to one license no. </p>