title: How to use Oracle's decode function in where clause
body: <p>I have a query with few filter criteria, one of them is get to the query as integer parameter. I want to use this filter only if this integer is > 0 
  I can't use NVL as it will never be null. How can I use <code>DECODE</code> in such case?</p>
  
  <pre><code>SELECT (columns list)
          FROM 
          AGREEMENT A
          WHERE 
          A.ACCOUNT = 545 
          AND A.GRP_ID = NVL(?,A.GRP_ID)
  </code></pre>
  
  <p>The parameter <code>?</code> I get is an Integer</p>