title: Is there a way to filter one database field based on another?
body: <p>I have one field which is <code>{customer.id}</code> and another which is <code>{side}</code> (that has the values "L" and "R") and I need to count the <code>{customer.id}</code> if <code>{side}</code> is either "L" or "R" but not both(xor) for the specific id.
  Example:</p>
  
  <pre><code>{customer.id}     {side}
     id1              L
     id1              R
     id2              L
     id2              R
     id3              L
     id4              R 
     id4              R
  </code></pre>
  
  <p>So I would like the result of the distinctcount for this example to be 2 (id3 and id4).</p>
  
  <p>Is it possible to achieve this filtering somehow in crystal reports?</p>