I want to delete duplication with condition from a table in PLSQL - oracle

Question

I want to delete the dup lines using PLSQL. The sample of the table is below
Policy #
Price
Dealno for Loan #
Price of Loan
PersonID
123
10
Loan123
1,000
abc
123
10
Loan123
3,000
abc
456
10
Loan456
500
xyz
456
10
Loan456
500
null
As you can see, in the case of Policy #123, I try to get the line with the highest amount of Price of Loan. Which mean the Price of Loan for 3,000.
For Policy #456, I want to get the one without null value.
Is there a way for me to achieve that in PLSQL.
Thank you

Answer 1

This query identifies if a row is OK (rn = 1) or if is is a duplicated copy (rn > 1) based on your definition
select POLICY#, PRICE, LOAN#, PRICE_LOAN, PERSON_ID,
row_number() over (partition by POLICY# order by PRICE_LOAN desc, PERSON_ID nulls last) as rn
from tab
;
POLICY# PRICE LOAN# PRICE_LOAN PER RN
---------- ---------- -------- ---------- --- ----------
123 10 loan123 3000 abc 1
123 10 loan123 1000 abc 2
456 10 loan4563 500 xyz 1
456 10 loan4563 500 2
Note that you use row_number where you partition by on the unique key and order by so that you get first the row that should be taken.
So to get the duplicates only you use this query
with rn as (
select POLICY#, PRICE, LOAN#, PRICE_LOAN, PERSON_ID,
row_number() over (partition by POLICY# order by PRICE_LOAN desc, PERSON_ID nulls last) as rn
from tab
)
select * from rn where rn > 1;
POLICY# PRICE LOAN# PRICE_LOAN PER RN
---------- ---------- -------- ---------- --- ----------
123 10 loan123 1000 abc 2
456 10 loan4563 500 2
Based on this you write the DELETE statement (enclose in BEGIN ... END if you insist in PL/SQL)
delete from tab where rowid in
(
with rn as (
select POLICY#, PRICE, LOAN#, PRICE_LOAN, PERSON_ID,
row_number() over (partition by POLICY# order by PRICE_LOAN desc, PERSON_ID nulls last) as rn
from tab
)
select rowid from rn where rn > 1
);
You may check if the delete worked fine ....
select * from tab;
POLICY# PRICE LOAN# PRICE_LOAN PER
---------- ---------- -------- ---------- ---
123 10 loan123 3000 abc
456 10 loan4563 500 xyz
... and commit