title: Use WHERE clause only if item is set, otherwise select all rows
body: <p>In my Apex Oracle application I have a report using this sql query:</p>
  <pre><code>select ID,
     NAME,
     ADDRESS,
     TYPE,
     COMPANY_ID as &quot;Company&quot;
  from WORKSTATIONS where COMPANY_ID = :P11_FILTER
  </code></pre>
  <p>which filters data by value of :P11_FILTER item. Now I need to select all rows if :P11_FILTER is not set or is NULL. How could I modify the where clause in order to achieve that?</p>