title: DATALENGTH() or ISNULL() to retrieve fields that are not null and not empty
body: <p>Quite simply, which of the following methods is better in a <code>WHERE</code> clause to retrieve records where the <code>FIELD_NAME</code> is <strong>NOT NULL</strong> and <strong>NOT Empty</strong></p>
  
  <pre><code>WHERE DATALENGTH(FIELD_NAME) &gt; 0
  </code></pre>
  
  <p>or</p>
  
  <pre><code>WHERE ISNULL(FIELD_NAME, '') &lt;&gt; ''
  </code></pre>
  
  <h3>Update</h3>
  
  <p>I have been informed that the first method gives spurious results for some types of fields... Agree?</p>