How to find the sum of a column

Question

I need to find the sum of a column and use it in a different column. The following is the example.
Column names: Feedback(Good, Avg, Poor), Count(no of good, no of avg, no of poor) and %age(Feedback/sum(feedback))
I want to find the sum in Java class and also calculate the last column in java class.
Please tell me some way to do it.

Answer 1

oh.. ok ..thanks for letting me know.. i will formulate the question in a proper way:
This is what my UI should look like:
Rating Count Percent
Excellent 2 20
Good 6 60
Poor 1 10
Bad 1 10
Now i have the following columns in the data base:
Meaning and feedback_rating.
So the following SQL Query:
SELECT hrl.meaning rating,
sum(decode(bcpi.feedback_rating, null, 0, 1)) counted
from cmp_cwb_person_info bcpi ,
hr_lookups hrl
group by hrl.meaning
will give me the result as
rating counted
Excellent 2
Good 6
Poor 1
Bad 1
Now I want a third column as percentage : Earlier we were doing this calculation in the sql query itself, so the query was like
SELECT hrl.meaning rating,
sum(decode(bcpi.feedback_rating, null, 0, 1)) counted,
sum(decode(bcpi.feedback_rating, null, 0, 1))/(max (select count (*) from cmp_cwb_person_info bcpi ,
hr_lookups hrl )) percent
from cmp_cwb_person_info bcpi ,
hr_lookups hrl
group by hrl.meaning
Hence the third column (percent) was calculated in the sql query itself.
But now i feel that the performance of the query could be improved if we get the first two columns from the database and the calculate the third column programatically in the java code.
So this is what I want to know. How can i do that?