update based on multiple rows in sql [closed] - sql

Question

Closed. This question needs to be more focused. It is not currently accepting answers.
Want to improve this question? Update the question so it focuses on one problem only by editing this post.
Closed 3 years ago.
Improve this question
PART LATESTPART RATE LATESTMONTHSALE status
A X 100 2019-06-01 N
B X 100 2019-07-01 N
C Y 200 2019-08-01 N
D Y 150 2019-08-01 N
E X 100 2019-09-01 N
update status as "Y" of PART when LATESTPART is same and RATE minimum
Eg. for PART C,D LATESTPART is same(Y) and rate of 'PART' D is minimum(150) then update part D status "Y".
If rate is same then check LATESTMONTHSALE. Update status of the PART having lastest month.
Eg. for PART A,B,E LATESTPART is same(X) and rate is also same then update PART E because 2019-09-01 is latest date.
i want result as.
PART LATESTPART RATE LATESTMONTHSALE status
A X 100 JUN_19 N
B X 100 JUL_19 N
C Y 200 AUG_19 N
D Y 150 AUG_19 Y
E X 100 SEP_19 Y

Answer 1

I think that you can do this with a correlated subquery that filters on the latest records per (part, latestpart) tuple and a not exists condition that filters on the record that has the lowest rate.
update mytable t set status = 'Y'
where
t.latestmonthsale = (
select max(t1.latestmonthsale)
from mytable t1
where t1.part = t.part and t1.latestpart = t.latestpart
)
and not exists (
select 1
from mytable t1
where
t1.part = t.part
and t1.latestpart = t.latestpart
and t1.latestmonthsale = t.latestmonthsale
and t1.rate < t.rate
)
In SQLServer, you can also do this with row_number() and an updatable cte:
with cte as (
select
status,
row_number()
over(partition by part, latestpart order by latestmonthsale desc, rate) rn
from mytable
)
update cte set status = 'Y' where rn = 1