title: How to insert case statement in where condition
body: <p>My query is below, What I need is when I pass -1 in parameter no condition should call else when other value are passes It should call the condition</p>
  
  <p>I have tried below query but its not working</p>
  
  <pre><code>SELECT RequestID
       , AgencyName
       , Contact
       , DeliveryAddress
       , ContactPhone
       , ContactEmailAddress
       , RequestDate
       , CASE WHEN RequestStatus=0 THEN 'Pending' 
              ELSE CASE WHEN RequestStatus=1 THEN 'Approved' 
                        ELSE 'Denied' 
                   END 
         END AS 'RequestStatus'
      FROM tblRequest 
      WHERE CASE WHEN @RequestStatus=-1 THEN '0'='0' 
                 ELSE RequestStatus= @RequestStatus 
            END
  </code></pre>