title: Oracle - Filter records based on input value
body: <p>In below sql statement, value for the person_id is dynamically passed.</p>
  
  <pre><code>SELECT * FROM person WHERE person_id = '&amp;PERSON_ID';
  </code></pre>
  
  <p>There is a requirement, when user enters % for person_id, all records should be returned. Simply it should execute following query:</p>
  
  <pre><code>SELECT * FROM person;
  </code></pre>
  
  <p>Can anyone know the trick?</p>