To automate query such that it works even during cross year.

Question

Hi all, please help....
Firstly, certain parameters need to be understood.
Our financial year ended this september and new
financial year begins October.
Month_ID
Aug'03 = 71
Sep'03 = 72
Oct'03 = 73
Nov'03 = 74
etc...
Month_Id increases continously regardless of new financial year.
Period_ID
11 (Aug
12 (Sep)
1 (Oct)Period changes to 1 again coz our coy's
financial year period starts in October.
Now, the main part of the SQL statement causing cross year problem is this:-
WHERE MONTH_ID BETWEEN MONTH_ID-(PERIOD_ID-1) AND MONTH_ID-1
Firstly, for last month September:-
Between Month_ID - (Period_ID-1) and Month_ID - 1
72 - (12-1) 72 - 1
=Between 61 and 71
The calculation is correct for September.
Now for October, this is the new financial year and the
Period_id has now changed from 12 to 1.Month_ID has now increased to 73.
Between Month_ID - (Period_ID-1) and Month_ID - 1
73 - (1-1) 73 - 1
= Between 73 and 72
This statement is obviously wrong.
Folks, is there anyway I could fine tune the SQL to automate this so that it works during all cross year periods?
Here is the actual full SQL statement just for your reference:-
SELECT
B.YEAR, B.PERIOD_ID-1,
ROUND(SUM(A.DEL_HC_TO_AMT),2) YTD_DEL_HC_TO_AMT, C.CUST_ID,
C.COUNTRY_ID, C.CUST_GROUP, C.FIN_GRP_ID
FROM
DWMART.DWHD10_SLS_DELIVERY A,
DWMART.DWHMAS_TME_MONTH B,
DWMART.DWHMAS_CUS_MASTER C
WHERE A.MONTH_ID BETWEEN B.MONTH_ID-(B.PERIOD_ID-1) AND B.MONTH_ID-1
AND A.ITEM_ID NOT LIKE 'FR%'
AND A.ITEM_ID NOT LIKE 'NON%'
AND TRUNC(SYSDATE) BETWEEN B.START_DATE AND B.END_DATE
AND A.CUST_ID = C.CUST_ID
GROUP BY B.YEAR, B.PERIOD_ID-1, C.CUST_ID, C.COUNTRY_ID, C.CUST_GROUP, C.FIN_GRP_ID
Thanx guys.

Answer 1

Its not clear what you are wanting to get back from your query.
If for october you want the full previous financial year, and the other months are currently correct, you could implement a case...
WHERE a.MONTH_ID BETWEEN
  case b.period_id
    when 1 then b.MONTH_ID - 12
    else b.MONTH_ID-(b.PERIOD_ID-1)
  end
  AND b.MONTH_ID-1