mysql> select * from issue;
+----+---------------------+-------+
| id | time                | count |
+----+---------------------+-------+
|  1 | 2012-04-01 08:15:00 |    12 |
|  2 | 2012-04-01 09:15:00 |    12 |
|  3 | 2012-04-01 08:25:00 |    12 |
|  4 | 2012-04-01 10:15:00 |    12 |
|  5 | 2012-04-01 09:15:00 |    12 |
+----+---------------------+-------+
5 rows in set (0.00 sec)

mysql> select concat(date_format(time, "%Y-%m-%d %k:00~"),  hour(time)+1, ":00")
 as 'time', sum(`count`) as 'count'
    -> from issue
    -> group by left(time, 13);
+------------------------+-------+
| time                   | count |
+------------------------+-------+
| 2012-04-01 8:00~9:00   |    24 |
| 2012-04-01 9:00~10:00  |    24 |
| 2012-04-01 10:00~11:00 |    12 |
+------------------------+-------+
3 rows in set (0.00 sec)

------解决方案--------------------
恩   group by left(time, 13);

------解决方案--------------------

select DATE_FORMAT(time,'%Y-%m-%d %H:00'),sum(count)
from issue
group by DATE_FORMAT(time,'%Y-%m-%d %H:00')

------解决方案--------------------
select Date_format(time,'%Y-%M-%d %H:00'),SUM(COUNT)
FROM issue
group byy DATA_FORMAR(time,'%Y-%m-%d %h:00)