SQL to compare records (status change) in table

Question

I have a table that contains history of a claim. Basically I'm looking at status changes and dates. Whenever someone updates a claim, the new row is loaded into the table I'm showing below. What I'm trying to obtain is all of the status changes for the column "c_sta_clm" I want to be able to capture the date "row_begin_dt" and both status change (PC to AC) & (AC to TE).

Any guidance on how to make this simple is hugely appreciated. I was thinking of making two volatile tables and joining on C_CLM, taking min status dates and comparing etc...

row_begin_dt                user                    c_clm          c_sta_clm
2009-10-08  ?       C5S2M                         09050012            PC
2009-10-24  ?       C5S2M                         09050012            AC
2009-10-28  ?       C1CMH                         09050012            AC
2010-10-30  ?       C1CMH                         09050012            AC
2011-05-19  ?       A9709                         09050012            AC
2011-06-09  ?       C6JEC                         09050012            AC
2011-10-07  ?       DAJ07                         09050012            TE
2011-11-04  ?       DAJ07                         0905001             TE

Answer 1

This should get you the records for 2009-10-24 and 2011-10-07.

select
    row_begin_dt,
    user,
    c_clm,
    c_sta_clm,
    -- Find the c_sta_clm of the previous row
    max(c_sta_clm) over (partition by c_clm order by row_begin_dt rows between 1 preceding and 1 preceding) as prev_c_sta_clm
from claims
-- Include only records which have a c_sta_clm different to that of the previous row
qualify c_sta_clm <> prev_c_sta_clm

Answer 2

One general way to do this is using correlated subqueries:

select
from (select c.*,
             (select top 1 from claims c2 where c2.c_clm = c.c_clm a and c2.row_begin_dt > c.row_begin_dt order by row_begin_dt
             ) as next_sta_clm
      from claim c2
     ) c
where next_sta_clm <> c_sta_clm

In many databases, you can do the same thing with the lag or lead function, but no all databases support them.

Answer 3

Something like

Select ToRecord.row_begin_dt From ClaimHistory FromRecord
inner join ClaimHistory ToRecord On ToRecord.c_clm = FromRecord.c_clm and ToRecord.row_begin_dt > FromRecord.row_begin_dt and ToRecord.c_sta_claim = 'AC'
Where FromRecord.c_sta_claim = 'PC'

would get PC to AC, didnlt know whether user column was significant, but bolting it in should be trivial. Seeing as you didn't say which DBMS, sql may require a twiddle.

Also this would pick up something like PC to XX to AC, which you didnt say anything about.