Need help subtracting two columns in Oracle SQL

What is the correct statement to subtract TARGET_TAT from NET_TAT from the SQL below?
Keep getting an error when using, round(TARGET_TAT-BA_VIEW_WO_SUMMARY.NET_TAT,0) DAYS_LEFT

sql
maximus1974Asked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

slightwv (䄆 Netminder) Commented:
You cannot use an alias in the same level you declared it.

So:
round(CASE EHEN ctd.TAT_DAYS IS NULL then 21 ELSE ctd.TAT_DAYS END-BA_VIEW_WO_SUMMARY.NET_TAT,0) DAYS_LEFT

or
wrap your select with the CASE statement and do the math outside:

select  round(TARGET_TAT-BA_VIEW_WO_SUMMARY.NET_TAT,0) DAYS_LEFT
from (
     select CASE EHEN ctd.TAT_DAYS IS NULL then 21 ELSE ctd.TAT_DAYS END TARGET_TAT ... from ...
)
1

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
maximus1974Author Commented:
Thank you slightwv. I am getting an error when testing the statement.error
0
maximus1974Author Commented:
Please disregard. Misspelled When.
0
slightwv (䄆 Netminder) Commented:
>>Please disregard. Misspelled When.

lol... I can't type!
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Query Syntax

From novice to tech pro — start learning today.