analytical functions - sql

Question

good afternoon, a question, how can I optimize the code, I don't know, maybe using oracle analytical functions :
-- tabledeuda : this table contains 2 months 202212 and 202211
SELECT B.*,
NVL(B.DEUDAPRESTAMO_PAGPER,0)-NVL(A.DEUDAPRESTAMO_PAGPER,0) AS SALE_CT -- current month - previous month
FROM tabledeuda B
LEFT JOIN tabledeuda A ON (A.CODLLAVE = B.CODLLAVE
AND A.CODMES = TO_NUMBER(TO_CHAR(ADD_MONTHS(TO_DATE(B.CODMES,'YYYYMM'),-1),'YYYYMM'))
AND A.financial_company = B.financial_company
AND A.CODMONEY=B.CODMONEY)
WHERE NVL(B.DEUDAPRESTAMO_PAGPER,0)>NVL(A.DEUDAPRESTAMO_PAGPER,0)
AND B.CODMES = &CODMES; ---> &CODMES 202212
OUTPUT

Answer 1

Looks like a candidate for lag analytic function.
Sample data is rather poor so it is unclear what happens when there's more data, but - that's the general idea.
Sample data:
SQL> with test (codmes, customer, deudaprestamo_pagper) as
2 (select 202212, 'T1009', 200 from dual union all
3 select 202211, 'T1009', 150 from dual
4 )
Query:
5 select codmes, customer,
6 deudaprestamo_pagper,
7 deudaprestamo_pagper -
8 lag(deudaprestamo_pagper) over (partition by customer order by codmes) sale_ct
9 from test;
CODMES CUSTO DEUDAPRESTAMO_PAGPER SALE_CT
---------- ----- -------------------- ----------
202211 T1009 150
202212 T1009 200 50
SQL>
If you want to fetch only the last row (sorted by codmes), you could e.g.
6 with temp as
7 (select codmes, customer,
8 deudaprestamo_pagper,
9 deudaprestamo_pagper -
10 lag(deudaprestamo_pagper) over (partition by customer order by codmes) sale_ct,
11 --
12 row_number() over (partition by customer order by codmes desc) rn
13 from test
14 )
15 select codmes, customer, deudaprestamo_pagper, sale_ct
16 from temp
17 where rn = 1;
CODMES CUSTO DEUDAPRESTAMO_PAGPER SALE_CT
---------- ----- -------------------- ----------
202212 T1009 200 50
SQL>