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with table1 (Userid, Task_id, Start, End, Total_Time) as (
VALUES
('User1', 'Task1', timestamp '2023-08-09 08:00:00', timestamp '2023-08-09 09:00:00', time '01:00:00'),
('User1', 'Task2', '2023-08-09 08:15:00', '2023-08-09 10:00:00', '01:45:00'),
('User2', 'Task1', '2023-08-09 08:30:00', '2023-08-09 10:00:00', '01:30:00'),
('User2', 'Task2', '2023-08-09 09:00:00', '2023-08-09 11:30:00', '02:30:00'),
('User1', 'Task3', '2023-08-09 11:15:00', '2023-08-09 13:00:00', '02:45:00'),
('User2', 'Task3', '2023-08-09 15:15:00', '2023-08-09 16:00:00', '00:45:00'),
('User2', 'Task1', '2023-08-09 15:20:00', '2023-08-09 16:00:00', '00:40:00')
),
-- is case when two tasks share the exact same period
distinct_periods as (
select distinct userid, start, end from table1
),
-- extend periods
periods (n, userid, start, end) as (
-- start with periods that are not preceded by an overlaping period
select 1, userid, start, end from distinct_periods t1
where not exists (
select * from distinct_periods t2
where t2.userid = t1.userid
and (t1.start > t2.start and t1.start <= t2.end
or t1.start = t2.start and t1.end > t2.end)
)
-- extend with those that overlap
union all
select n+1, periods.userid, periods.start, distinct_periods.end
from periods, distinct_periods
where
distinct_periods.userid = periods.userid
and distinct_periods.start between periods.start and periods.end
and distinct_periods.end > periods.end
-- and n < 10
),
-- add a rank by end date descending so that the widest period has rank 1
with_rank as (
| USERID | TIME_BUSY |
|---|---|
| User1 | 03:45:00 |
| User2 | 03:45:00 |