Consecutive dates Sequence by criteria - mysql

Question

I have a table that holds tasks like the following example:
id user_id project_id done_at duration type
1 13 15 2014-08-11 03:00:00 1
2 13 15 2014-08-11 04:00:00 1
10 13 15 2014-08-12 04:00:00 1
3 13 15 2014-08-12 08:00:00 2
5 13 13 2014-08-13 08:00:00 1
7 13 15 2014-08-14 04:00:00 1
8 13 15 2014-08-18 08:00:00 1
9 13 15 2014-08-19 08:00:00 2
How can i get start/end sequences of consecutive done_at column by user, project and type like this:
user_id project_id type start_done_at end_done_at duration
13 15 1 2014-08-11 2014-08-12 11:00:00
13 15 2 2014-08-12 2014-08-12 08:00:00
13 13 1 2014-08-13 2014-08-14 12:00:00
13 15 1 2014-08-18 2014-08-18 08:00:00
13 15 2 2014-08-19 2014-08-19 08:00:00
I already tried following this example: http://www.artfulsoftware.com/infotree/qrytip.php?id=76 however i didnt make to get the duration correctly.
My current query is this:
SELECT task.user_id as user_id, task.done_at as start_done_at, MIN(task2.done_at) as end_done_at, task.project_id as project_id, task.timeoff_type_id as timeoff_type, SEC_TO_TIME(SUM(TIME_TO_SEC(task.duration))) as duration
FROM tasks task
LEFT JOIN tasks task1 ON task.done_at = task1.done_at + 1
AND task.user_id = task1.user_id
AND task.project_id = task1.project_id
AND task.timeoff_type_id = task1.timeoff_type_id
LEFT JOIN tasks task2 ON task.done_at <= task2.done_at
AND task.user_id = task2.user_id
AND task.project_id = task2.project_id
AND task.timeoff_type_id = task2.timeoff_type_id
LEFT JOIN tasks task3 ON task2.done_at = task3.done_at -1
AND task2.user_id = task3.user_id
AND task2.project_id = task3.project_id
AND task2.timeoff_type_id = task3.timeoff_type_id
WHERE task1.done_at IS NULL
AND task2.done_at IS NOT NULL
AND task3.done_at IS NULL
GROUP BY task.user_id, task.project_id, task.timeoff_type_id, task.done_at

Answer 1

select
user_id, project_id,
min(done_at) as start_done_at,
max(done_at) as end_done_at,
sec_to_time(sum(time_to_sec(duration))) as duration
from (
select
t.*,
#gn := if(timestampdiff(day, #prev_date, done_at) between 0 and 1 and #prev_type = type and #prev_project = project_id, #gn, #gn + 1) as group_number,
#prev_date := done_at,
#prev_type := type,
#prev_project := project_id
from
t
, (select #prev_project := null, #prev_date := null, #prev_type := null, #gn := 0) var_init
order by project_id, done_at, duration
) sq
group by group_number
see it working live in an sqlfiddle