Query for Excel or DB2 - sql

Question

How can I write this as formula in Excel, and also how to use this logic in DB2 query :
IF:
Month(max(A_dt)) <= month(B_dt)
that is being used
THEN:
day=01, month=month(A_dt), year=year(B_dt) + 1
ELSE:
day=01 Month=Month(A_dt) Year=Year(B_dt)

Answer 1

This question is quite vague and hard to answer without any idea of table structure and data set. Following the logic that you outline, year is the only output that changes based on the conditional.
The below contains three simple case statements to handle your conditional. The first two are completely pointless due to returning the same response no matter pass or fail (per your logic above), but I included them still just to illustrate the point as it may help you understand if the conditional is confusing you.
I would suggest reading up on the db2 manual for your specific flavor or doing some intro sql tutorials. The case is pretty fundamental and quite useful in query writing.
select
_key
,case when month(max(a_dt)) <= month(b_dt)
then 01
else 01
end as day
,case when month(max(a_dt)) <= month(b_dt)
then month(a_dt)
else month(a_dt)
end as month
,case when month(max(a_dt)) <= month(b_dt)
then year(b_dt) + 1
else year(b_dt)
end as year
from
your_table