title: Subtracting sql time value with a given time value
body: <p><strong>My Query</strong></p>
  
  <pre><code> SELECT DATE, SEC_TO_TIME( SUM( TIME_TO_SEC(  `total_hours` ) ) ) AS total
  FROM work_details
  WHERE  `employee_id` =  '28'
  AND DATE
  BETWEEN  '2012-02-01'
  AND  '2012-02-29'
  GROUP BY DATE
  ORDER BY DATE
  </code></pre>
  
  <p>// Which takes total hours worked for a given employee in given date from database table work_details ,total_hours is of time type.</p>
  
  <p><strong>Result</strong></p>
  
  <pre><code>DATE    total
  2012-02-01  04:19:50
  2012-02-02  07:38:21
  2012-02-06  07:43:24
  2012-02-07  07:21:36
  2012-02-08  07:38:45
  2012-02-09  06:05:22
  2012-02-10  07:28:00
  2012-02-13  07:37:38
  2012-02-14  07:37:22
  2012-02-15  07:35:10
  2012-02-16  07:29:13
  2012-02-17  07:07:23
  2012-02-20  07:40:32
  2012-02-21  07:43:32
  2012-02-22  07:36:40
  2012-02-23  07:37:57
  2012-02-24  07:35:04
  2012-02-27  09:54:02
  2012-02-28  07:41:35
  2012-02-29  04:01:11
  </code></pre>
  
  <p>I need to retrieve the dates in which the the total working hours which are <strong>&lt;</strong> 4 hours,so that i can count that days as half leaves. Any Help ??</p>
  
  <p>I tried this query too, i have given 8 instead of 4,because my table consists no data less than 4 now.</p>
  
  <pre><code>SELECT DATE, SEC_TO_TIME( SUM( TIME_TO_SEC(  `total_hours` ) ) ) AS total, 
  CASE WHEN SEC_TO_TIME( SUM( TIME_TO_SEC(  `total_hours` ) ) ) &lt; ( 3600 *8 ) 
  THEN 1 
  ELSE 0 
  END AS half_day
  FROM work_details
  WHERE  `employee_id` =  '28'
  AND DATE
  BETWEEN  '2012-02-01'
  AND  '2012-02-29'
  GROUP BY DATE
  </code></pre>
  
  <p>Result</p>
  
  <pre><code>DATE    total   half_day
  2012-02-01  07:19:50    0
  2012-02-02  07:38:21    0
  2012-02-06  07:43:24    0
  2012-02-07  07:21:36    0
  2012-02-08  07:38:45    0
  2012-02-09  06:05:22    0
  2012-02-10  07:28:00    0
  2012-02-13  07:37:38    0
  2012-02-14  07:37:22    0
  2012-02-15  07:35:10    0
  2012-02-16  07:29:13    0
  2012-02-17  07:07:23    0
  2012-02-20  07:40:32    0
  2012-02-21  07:43:32    0
  2012-02-22  07:36:40    0
  2012-02-23  07:37:57    0
  2012-02-24  07:35:04    0
  2012-02-27  09:54:02    0
  2012-02-28  07:41:35    0
  2012-02-29  08:01:11    0
  </code></pre>