Computing diff. between two rows and more...

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Computing diff. between two rows and more...

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Novalobster
Starting Member

2 Posts

Posted - 2013-07-06 : 13:54:03

Hi there,

I encountered a tricky problem. The original data, say, table_o, is shown below:

Ids Status Date
ID1 4 02-May-13
ID1 3 10-May-13
ID1 2 16-May-13
ID1 1 20-May-13
ID2 3 08-May-13
ID2 2 10-May-13
ID2 1 19-May-13

The final resulting table, e.g., table_f, is:

Ids 4->3 3->2 2->1
ID1 8 6 4
ID2 NULL 2 9

The values in the final table are the days used by each ID transferring from status i to status i-1. E.g., ID uses 8 days (10-May-13 - 2-May-13) to go to status 3 from status 4.

It is hard for me to come up with a table like the final table, although I know that the difference between two adjacent rows can be computed by using self-join and timediff(). Thanks for your input!

bitsmed
Aged Yak Warrior

545 Posts

Posted - 2013-07-06 : 19:47:31

Maybe you can use this:


select o1.ids
      ,sum(case when o1.status=3 then datediff(day,o2.date,o1.date) else 0 end) as d3
      ,sum(case when o1.status=2 then datediff(day,o2.date,o1.date) else 0 end) as d2
      ,sum(case when o1.status=1 then datediff(day,o2.date,o1.date) else 0 end) as d1
  from table_o as o1
       left outer join table_o as o2
                    on o2.ids=o1.ids
                   and o2.status=o1.status+1
 where o1.status between 1 and 3
 group by o1.ids
 order by o1.ids

ps.: there might be syntax errors, as I don't have access to database at the moment.

Novalobster
Starting Member

2 Posts

Posted - 2013-07-06 : 20:16:45

Thank you. Probably I will change d3 to "4 to 3", d2 to "3 to 2", and so on.

visakh16
Very Important crosS Applying yaK Herder

52326 Posts

Posted - 2013-07-07 : 10:21:52

[code]
declare @t table
(
Ids varchar(5),
[Status] int,
[Date] date
)
insert @t
values
('ID1', 4, '02-May-13'),
('ID1', 3, '10-May-13'),
('ID1', 2, '16-May-13'),
('ID1', 1, '20-May-13'),
('ID2', 3, '08-May-13'),
('ID2', 2, '10-May-13'),
('ID2', 1, '19-May-13')

SELECT IDs,
DATEDIFF(dd,MAX(CASE WHEN Status=4 THEN date END),MAX(CASE WHEN Status=3 THEN date END)) AS [4-3],
DATEDIFF(dd,MAX(CASE WHEN Status=3 THEN date END),MAX(CASE WHEN Status=2 THEN date END)) AS [3-2],
DATEDIFF(dd,MAX(CASE WHEN Status=2 THEN date END),MAX(CASE WHEN Status=1 THEN date END)) AS [2-1]
FROM @t
CROSS JOIN (VALUES (0),(-1),(-2),(-3))t1(n)
GROUP BY IDs--,[Status]+n

output
-----------------------------------
IDs 4-3 3-2 2-1
-----------------------------------
ID1 8 6 4
ID2 NULL 2 9

[/code]

------------------------------------------------------------------------------------------------------
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