appointment

问题 I have a table in mysql like this: +------------+------------+------------+------------+ | date | user_id | start_hour | end_hour | +------------+------------+------------+------------+ | 2010-12-15 | 20 | 08:00:00 | 08:15:00 | | 2010-12-15 | 20 | 14:00:00 | 14:30:00 | | 2010-12-15 | 20 | 17:00:00 | 17:45:00 | +------------+------------+------------+------------+ and I try to extract the time range of the time of users I found and example here, but I can't make that work on hours I tried the