title: Subquery in PL/SQL returning NO_DATA_FOUND
body: <p>A PL/SQL query I am looking at uses a subquery when determining a count of records:</p>
  
  <pre><code>SELECT COUNT(*)
  INTO v_seqn
  FROM SIPR.KDX KDX
  WHERE KDX.KDX_STUC NOT IN ( SELECT ADD1.ADD_ADID
                              FROM SIPR.MEN_ADD ADD1
                              WHERE ADD1.ADD_ADID = KDX.KDX_STUC)
  AND KDX.KDX_STUC = v_stud_id
  AND KDX.KDX_SITS = 'A';
  </code></pre>
  
  <p>If the subquery returns no records, will this cause a NO_DATA_FOUND exception which can be handled, or is it perfectly valid and will simply return a null for the "NOT IN" clause of the main query and result in a count of 0.</p>
  
  <p>Thanks.</p>