Subtracting two rows from the same column

Question

Hi,
I have the following table with about 6000 rows of different year_month but I am compare and subtract v
Organization     Year_month     Contribution
Kano     JAN-2011     200000
KADUNA     JAN-2011     300000
ABUJA     JAN-2011     400000
Kano     FEB-2011     300000
KADUNA     FEB-2011     200000
ABUJA     FEB-2012     600000
I want to select a year_month at run time to subtract the contribution of the first year_month from the contribution of the second year_month and give me the result as shown in the following table
Organization     JAN-2011     FEB-2011     diffrence
Kano     200000     300000     -100000
KADUNA     300000     200000     100000
ABUJA     400000     600000     -200000
Here is my code returning too many va
create or replace function "GET_MONTHLY_VALUE"
(q_name in VARCHAR2,
hmoCode in VARCHAR2)
return VARCHAR2
is
c1 number;
begin
select NHIS_CONTRIBUTION into c1 from CONTRIBUTION_MGT where upper(YEAR_MONTH)=upper(q_name) and upper(ORGANIZATION)=upper(hmoCode);
return c1;
exception when NO_DATA_FOUND THEN
return null;
end;
------a call to the above function:
create or replace function process_cont_monthly return varchar
is
Cursor cont_cursor is select ORGANIZATION from CONTRIBUTION_MGT;
begin
for
cont_rec in cont_cursor loop
select GET_MONTHLY_VALUE(:p26_month,cont_rec.ORGANIZATION) first, GET_MONTHLY_VALUE(:p26_month2,cont_rec.ORGANIZATION) second,
abs(GET_MONTHLY_VALUE(:p26_month,cont_rec.ORGANIZATION)-GET_MONTHLY_VALUE(:p26_month2,cont_rec.ORGANIZATION)) Diffrence
from CONTRIBUTION_MGT;
end loop;
commit;
end;
I became totally confused and don’t know what to do next
Any help and better guide is appreciated

Answer 1

Hi,
Here's one way:
WITH    months_wanted     AS
     SELECT     1 AS col, TO_DATE ('JAN-2011', 'MON-YYYY') AS month     FROM dual     
    UNION ALL
     SELECT     2 AS col, TO_DATE ('FEB-2011', 'MON-YYYY') AS month     FROM dual     
,     pivoted_data     AS
     SELECT       c.organization
     ,       NVL (SUM (CASE WHEN m.col = 1 THEN c.contribution END), 0)     AS total_1
     ,       NVL (SUM (CASE WHEN m.col = 2 THEN c.contribution END), 0)     AS total_2
     FROM       months_wanted     m
     JOIN       contribution_mgt  c ON  c.year_month >=            m.month
                                 AND c.year_month < ADD_MONTHS (m.month, 1)
SELECT    organization
,       total_1
,       total_2
,       total_1 - total_2     AS difference
FROM       pivoted_data
ORDER BY  organization
;I assume that the year_month column is a DATE. Date information always belongs in DATE columns.
As written, the two months do not need to be consecutive. If you always want consectuive months, this can be re-written so that you only have to enter the first month, not both of them.
I hope this answers your question.
If not, post a little sample data (CREATE TABLE and INSERT statements, relevant columns only) for all tables involved, and also post the results you want from that data.
Point out a few places where the query above is giving the wrong results, and explain, using specific examples, how you get those results from that data in those places. If you changed the query at all, post your code.
Always say which version of Oracle you're using.
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