Reg: Complex query requirement-

Question

Hi Experts,
I am having a query requirement which seems to be kind-of complex. Below I try to provide the pseudo-code:
-->>-- CASE (1)
IF EXISTS (
select new_amt
from table_stp stp
where stp.chng_dt = (
  select MAX(a.chng_dt)
  from table_stp stp
  where
   stp.chng_dt <= due_dt
   and stp.new_amt IS NOT NULL
-->>-- CASE (2)
ELSE IF EXISTS(
select old_amt
from table_stp stp
where stp.chng_dt = (
  select MIN(a.chng_dt)
  from table_stp stp
  where
   stp.chng_dt <= due_dt
   and stp.old_amt IS NOT NULL
ELSE 0
Some sample scenario -
LNO CHNG_DT  NEW_AMT OLD_AMT
1 12-01-2013 100  null
1 13-01-2013 200  666
1 14-01-2013 null 777
2 17-01-2013 null 555
2 18-01-2013 null 888
2 19-01-2013 null 999
Output should be:
1     13-01-2013     200      666 -->>-- case 1
2     17-01-2013     null     555 -->>-- case 2
Please let me know if you need any other clarification.
Could you please help me with this?
Help much appreciated.
Thanks,
Ranit
(on Oracle 11.2.0.3.0)

Answer 1

Hi Frank,
I guessed that my initial post will need some additional inputs. Let me try to describe my requirement more clearly:
Sample data --
with table_stp(LNO,CHNG_DT,NEW_AMT,OLD_AMT,col1,col2,col3,col4) as(
    select 1, TO_DATE('12-01-2013','dd-mm-yyyy'), 100, NULL, 11,12,13,14 from dual UNION ALL
    select 1, TO_DATE('13-01-2013','dd-mm-yyyy'), 200, 666, 21,22,23,24 from dual UNION ALL
    select 1, TO_DATE('14-01-2013','dd-mm-yyyy'), NULL, 777, 31,32,33,34 from dual UNION ALL
    select 2, TO_DATE('17-01-2013','dd-mm-yyyy'), NULL, 555, 41,42,43,44 from dual UNION ALL
    select 2, TO_DATE('18-01-2013','dd-mm-yyyy'), NULL, 888, 51,52,53,54 from dual UNION ALL
    select 2, TO_DATE('19-01-2013','dd-mm-yyyy'), NULL, 999, 61,62,63,64 from dual    
select *
from table_stp;
My expected output --
1     13-01-2013     200      666     21     22     23     24 -->>-- case 1
2     17-01-2013     null     555     41     42     43     44 -->>-- case 2
Logic --
(1) First, we need to check if Case - 1 satisfies or not.
(1.1) If Yes, do some task.
(1.2) If Not, check if Case - 2 satisfies or not.
     (1.2.1) If Yes, do some task.
     (1.2.2) If Not, set value = 0
Case - 1)
First, all records with "NEW_AMT" as null are eliminated and we need to fetch the value "NEW_AMT" with maximum "CHNG_DT".
So, first output record is scenario Case - 1.
Case - 2)
If all values for a LNO is null for column "NEW_AMT", we need to look into column "OLD_AMT" for the value with minimum "CHNG_DT"
Second output record lies here, because - all record values for column "NEW_AMT" is null, we need to consider column "OLD_AMT" for values,
Still, if all values in OLD_AMT is null, set = 0
Hope this gives a better understanding, else please let me know.