title: Not null property value search in marklogic
body: <p>I want to search documents from the query console based on some property which is not null. Lets say this is the json documents i have.</p>
  <blockquote>
  <p>{ &quot;a1&quot; : &quot;1234&quot;, &quot;a2&quot; : &quot;abc&quot;, &quot;a3&quot; : null, &quot;a4&quot; : &quot;mno&quot; }</p>
  <p>{ &quot;a1&quot; : &quot;1235&quot;, &quot;a2&quot; : &quot;xyz&quot;, &quot;a3&quot; : &quot;value&quot;, &quot;a4&quot; : &quot;mno&quot; }</p>
  </blockquote>
  <p>I can query documents based on property like this</p>
  <pre><code>cts:search(fn:collection(), cts:json-property-value-query(&quot;a3&quot;,&quot;value&quot;));
  </code></pre>
  <p>I am not able to use <strong>not equal logical operator</strong> with this query. Can anybody let me know, if i have to search documents based on property <strong>a3</strong> which is not null then what has to be the query ?</p>