TV Scheduled Items List

Question

Dear All,
I need to distinguish between the different sequential groups of the scheduled TV items, i.e. if I have one item scheduled at 06:00am with a duration of 01:00 hour
and another one, scheduled right after, at 07:00am with a duration of 00:30 hour, I want to have their sequential group id = 1, if I have another sequential group at the same day, i.e. item scheduled at 10:00am with a duration of 01:00 hour and then another one scheduled at 11:00, then they should have an id of 2.
Thought I can do it easy, using RANK() over PARTITION BY or so, but failed. Please advise.
Hereby is attached an example with the excpected sequential group id.
Many thanks in advance,
WITH scheduled_items AS (
SELECT 1 AS segment_id,
21600 AS local_time,
3600 AS scheduled_duration,
1 AS expected_seq_group_id
FROM dual
UNION ALL
SELECT 2,28800,1800,2
FROM dual
UNION ALL
SELECT 3,28800+1800,900 ,2
FROM dual
UNION ALL
SELECT 4,28800+1800+900,3600 ,2
FROM dual
UNION ALL
SELECT 5,28800+1800+900+3600,1800 ,2
FROM dual
UNION ALL
SELECT 6,40000,1800 ,3
FROM dual
UNION ALL
SELECT 7,40000+1800,600 ,3
FROM dual
UNION ALL
SELECT 8,40000+1800+600,3600,3
FROM dual)
SELECT * FROM scheduled_items;

Answer 1

NOT TESTED ! (no database access on weekends)
with
flagging as
(select the_item,the_start,the_duration,
        case when the_start + the_duration = lead(the_start,1) over (order by the_start)
             then 1
        end look_forth
        case when the_start = lag(the_start,1) over (order by the_start) + lag(the_duration,1) over (order by the_start)
             then 1
        end look_back
   from your_table
marking as
(select the_item,the_start,the_duration,
        case when (look_forth = 1 and look_back is null 0) or coalesce(look_forth,look_back) is null
             then 'new_segment'
        end the_segment
   from flagging
ranking as
(select the_item,the_start,the_duration,
        case when the_segment is not null
             then dense_rank() over (order by the_start)
        end the_segment
   from marking
select the_item,the_start,the_duration,
       last_value(the_segment ignore nulls) over (order by the_start) the_segment
-- not very sure about last_value - never done without partition by ...
  from rankingRegards
Etbin