title: Query that works with MariaDB but fails with a syntax error on MySQL
body: <p>This query works on MariaDB, but not MySQL. I get a error: <code>You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'integer) HOUR</code></p>
  
  <p>This is a really dense query. So, even though I've looked through the manual I've had trouble identify which function is actually causing the issue.</p>
  
  <pre><code>SELECT  1 AS one
  FROM sched_walks INNER JOIN walks ON walks.id = sched_walks.walk_id
  WHERE sched_walks.d_acc = 1
    AND sched_walks.docent_id = 6
    AND (sched_walks.id != 714)
    AND (
      scheduled_for_utc &lt;= '2018-03-17 14:34:31.000000'
        AND
      DATE_ADD(
        scheduled_for_utc,
        INTERVAL CONVERT(REPLACE(COALESCE(sched_duration, walks.duration), ' hours', ''), integer) HOUR
      ) &gt;= '2018-03-17 12:34:31.000000'
    )
  LIMIT 1
  </code></pre>