title: Oracle NVL function not allows second parameter as datetime
body: <pre><code>select nvl(trunc(null),trunc(sysdate)) from dual;
  </code></pre>
  
  <p>While executing above query i am getting following error</p>
  
  <pre><code>ORA-00932: inconsistent datatypes: expected NUMBER got DATE
  </code></pre>
  
  <p>look like when i take string or number instead of <code>trunc(sysdate)</code> it run fine.</p>