title: How can I get the sum of multiple datetime values?
body: <p>I have a query such that the query's result is:</p>
  
  <pre><code>SELECT CONVERT(VARCHAR(8),(MAX(END_TIME)-MIN(START_TIME)),108) as DURATION WHERE ... GROUP BY TITLE
  </code></pre>
  
  <p>For each title, <code>DURATION</code> is different. The query returns:</p>
  
  <pre><code>DURATION
  00:16:14
  00:00:00
  00:01:30
  00:16:25
  00:09:34
  00:00:01
  01:04:04
  00:00:28
  00:00:12
  00:06:11
  00:26:38
  00:31:44
  00:02:16
  00:03:22
  00:09:39
  00:03:20
  00:03:43
  00:09:33
  00:08:05
  00:06:58
  00:25:29
  01:55:30
  00:03:02
  00:00:18
  00:06:09
  00:07:26
  00:25:43
  00:00:16
  00:26:58
  02:09:38
  00:57:56
  00:00:45
  00:00:00
  00:07:24
  00:00:54
  00:00:27
  00:01:28
  00:07:14
  00:00:19
  01:43:25
  00:58:23
  00:02:29
  02:19:48
  00:09:06
  05:12:15
  02:27:15
  00:56:47
  00:02:24
  </code></pre>
  
  <p>I need the sum of these values; how can I get it?</p>