title: when to use "and" statement in informix DB
body: <p>i have a problem in my SQL statement where the situation is I need to choose the data which have to meet several criteria. </p>
  
  <p>Question: How to determine existing old company - Lodgement of (F557 &amp; F559) or  (F558 &amp; F559) or (F557 &amp; F55) </p>
  
  <p>my SQL :</p>
  
  <pre><code>SELECT * from roclodgingdetails 
  WHERE(vchformtrx='559' AND vchformtrx='557') 
  OR (vchformtrx='558' AND vchformtrx='559') 
  OR (vchformtrx='557' AND vchformtrx='55')
  </code></pre>
  
  <p>but this statement give me the result empty, even there is data meet the condition.</p>