Time Span?

Question

I am trying to get the net days for a time span, starting from first step through to the last step. I have a few issues that I have to account for:
•     The problem is overlap time. Some steps overlap; with their start days coming before the end of the previous step.
•     There could be gaps from end of 1 step till start of the next.
I know I could min and max step days or count total days from table but that does not take the overlap into consideration. I have provided an example below.
CREATE TABLE claims_step_table ( 
table_id       INTEGER PRIMARY KEY,
record_id      NUMBER, 
step_code      VARCHAR2(20 Byte),
start_date     DATE,
end_date       DATE,
days           NUMBER
truncate table claims_step_table;
INSERT INTO claims_step_table VALUES (1,  123456,'P96','01-JAN-09','10-JAN-09',10);
INSERT INTO claims_step_table VALUES (2,  123456,'L61','10-JAN-09','15-JAN-09',5);
INSERT INTO claims_step_table VALUES (3,  123456,'H45','12-JAN-09','20-JAN-09',8);
INSERT INTO claims_step_table VALUES (4,  123456,'O87','10-FEB-09','15-FEB-09',5);
COMMIT;
P96      |----------- 10 --------|
L61                              |-----5-----|
H45                                   |--------8----------|
O87                                                                      |-----5-----|So the net should be 25 days because there is a 3 day overlap between step L61 and H45. Thanks for your help ahead of time.
Rich
GOOD CATCH, my fault record #4 should have been in FEB, cut and paste error.
Edited by: LostOne on Oct 15, 2009 8:19 AM

Answer 1

Using the tabibitosan method:
with    cst as (select 1 table_id, 123456 record_id, 'P96' step_code, to_date('01/01/2009', 'dd/mm/yyyy') start_date, to_date('10/01/2009', 'dd/mm/yyyy') end_date, 9 days from dual union all
                select 2 table_id, 123456 record_id, 'L61' step_code, to_date('10/01/2009', 'dd/mm/yyyy') start_date, to_date('15/01/2009', 'dd/mm/yyyy') end_date, 5 days from dual union all
                select 3 table_id, 123456 record_id, 'H45' step_code, to_date('12/01/2009', 'dd/mm/yyyy') start_date, to_date('20/01/2009', 'dd/mm/yyyy') end_date, 8 days from dual union all
                select 4 table_id, 123456 record_id, 'O87' step_code, to_date('22/01/2009', 'dd/mm/yyyy') start_date, to_date('27/01/2009', 'dd/mm/yyyy') end_date, 5 days from dual union all
                select 5 table_id, 123457 record_id, 'P96' step_code, to_date('22/02/2009', 'dd/mm/yyyy') start_date, to_date('24/02/2009', 'dd/mm/yyyy') end_date, 2 days from dual union all
                select 6 table_id, 123457 record_id, 'L61' step_code, to_date('01/01/2009', 'dd/mm/yyyy') start_date, to_date('11/01/2009', 'dd/mm/yyyy') end_date, 10 days from dual union all
                select 7 table_id, 123455 record_id, 'L61' step_code, to_date('18/01/2009', 'dd/mm/yyyy') start_date, to_date('19/01/2009', 'dd/mm/yyyy') end_date, 5 days from dual union all
                select 8 table_id, 123457 record_id, 'H45' step_code, to_date('02/01/2009', 'dd/mm/yyyy') start_date, to_date('05/01/2009', 'dd/mm/yyyy') end_date, 5 days from dual union all
                select 9 table_id, 123455 record_id, 'H45' step_code, to_date('22/01/2009', 'dd/mm/yyyy') start_date, to_date('27/01/2009', 'dd/mm/yyyy') end_date, 5 days from dual),
-- end of mimicking your data
tabibitosan as (select table_id,
                       record_id,
                       step_code,
                       start_date,
                       end_date,
                       dense_rank() over (order by start_date, end_date, table_id) -
                         row_number() over (partition by record_id order by start_date, end_date) difference
                from   cst),
    results as (select record_id,
                       max(end_date) - min(start_date) no_of_days
                from tabibitosan
                group by record_id,
                         difference)
select record_id,
       sum(no_of_days) total_days
from   results
group by record_id
order by record_id;
RECORD_ID TOTAL_DAYS
    123455          6
    123456         24
    123457         12NB. you had 10 days covering 1st Jan - 10th Jan, but 5 days covering 10th Jan - 15th Jan - this isn't consistent!
Regardless, you do not need to store the number of days difference in the table - it only encourages errors like that! Just calculate the difference on the fly.