decode and sign sql ..

I had to re-open an already closed question where sujith80 gave a solution for decode problem
Problem description
I want to write a sql to check the value of a field greater than zero and then do min (start date) if the value (of unit ) greater than zero and also do max(end date) for the same condition if the units is greater than zero
I am inserting the start and end to another table so for start date I should check
if unit >0 then
min (start date)
similarly for end date I should check
if unit >0 then
max(end date)

Solution proposed
select X.unit, decode(sign(unit),1,st_dt, NULL), decode(sign(unit),1,end_dt, NULL)
from <your table> X,
(select min(start_date) st_dt, max(end_date) end_dt from <your table> ) Y
/

I applied this solution and having a problem, in the above decode if the unit is >0 then the dates min and max worked, in the data there are units <0 rows that are existing and it shows up as null start date (st_dt) and null end date (end_dt), since I am writing a view statement from this query I do not wan them to appear in the view and also I want only for the date sake to fetch the min and max dates for unit >0, but if the rows has units <0 I dont want them to show up and the total amount should have included the rows having units <0

for example if I have 3 rows as data set and let us they are
unit            start date               end date
100          01-jan-07                 31-jan-07
200          01-feb-07                 28-feb-07
-100         01-mar-07                 31-mar-07
then for the start and end dates I need to get min (start date) and max ( end date) for unit >0
01-jan-07 and end date 28-feb-07
and the total should be 300-100 = 200
mahjagAsked:
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.

mahjagAuthor Commented:
So i want to add my expected result - view having columns

Total unit         start date           end date
200                   01-jan-07         28-feb-07
0
mahjagAuthor Commented:
Looks like I got away with the problem by doing this

select max(decode(sign(unit),1,st_dt, NULL), decode(sign(unit),1,end_dt, NULL))
to avoid group by the whole decode statement and now I got what I want - but it looks to me as pseudo solution by wrapping the aggregate max over the decode and sign as it means nothing.. I will wait for folks to jump in on the solution - nevertheless I found the above work around..
0
awking00Commented:
select sum(u.unit), x.st_dt, x.end_dt
from your_tbl u,
(select min(st_dt) st_dt
       ,max(end_dt) end_dt
 from your_tbl
 where unit > 0) x
group by x.st_dt, x.end_dt;
0

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
mahjagAuthor Commented:
Hi awking00

I ran the sql and I got the row that has amount = 0, I am trying to avoid this ..
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
Oracle Database

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.