MySql разница между двумя отметками времени в днях?

Как я могу узнать разницу между двумя отметками времени в днях? Должен ли я использовать для этого столбец datetime?

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Я переключил свой столбец на datetime. Кажется, простое вычитание не дает мне результата за несколько дней.

mysql> SELECT NOW(), last_confirmation_attempt, NOW() - last_confirmation_attempt AS diff  FROM DateClubs HAVING diff IS NOT NULL ;
+---------------------+---------------------------+-----------------+
| NOW()               | last_confirmation_attempt | diff            |
+---------------------+---------------------------+-----------------+
| 2010-03-30 10:52:31 | 2010-03-16 10:41:47       | 14001084.000000 |
+---------------------+---------------------------+-----------------+
1 row in set (0.00 sec)

Я не думаю, что diff находится в секундах, потому что, когда я делю diff на количество секунд в день (86 400), я не получаю разумного ответа:

mysql> SELECT NOW(), last_confirmation_attempt, ( NOW() - last_confirmation_attempt) / 86400 AS diff  FROM DateClubs HAVING diff IS NOT NULL ;
+---------------------+---------------------------+----------------+
| NOW()               | last_confirmation_attempt | diff           |
+---------------------+---------------------------+----------------+
| 2010-03-30 10:58:58 | 2010-03-16 10:41:47       | 162.0568402778 |
+---------------------+---------------------------+----------------+
1 row in set (0.00 sec)

SELECT DATEDIFF('2010-10-08 18:23:13', '2010-09-21 21:40:36') AS days;
+------+
| days |
+------+
|   17 |
+------+

 SELECT TIMEDIFF(`call_end_time`, `call_start_time`) as diff from tablename;

     diff
     - - -
    00:05:15

SELECT TIMESTAMPDIFF(SECOND,'2010-09-21 21:40:36','2010-10-08 18:23:13')/86400 AS diff