title: SQL query to find people where age is below a certain value
body: <p>I am attempting to find all persons who are below the age of 40, I have attempted a query after looking through documentation:</p>
  
  <pre><code>SELECT p.FirstName, p.LastName
  FROM Person AS p
  WHERE 40 &lt;= DATEDIFF(CURRENT DATE, p.DateOfBirth, 'YEAR');
  </code></pre>
  
  <p>However I am returned an error stating:</p>
  
  <pre><code>No authorized routine named "DATEDIFF" of type "FUNCTION" having compatible arguments was 
  found
  </code></pre>
  
  <p>Yet I have seen DATEDIFF used in DB2 SQL before.</p>