Question : How I can simplify a series of nested case statements in a MS SQL 2005 query

Hello,

I'm working on an average debt oustanding query and I have my debt principal balances split into months (columns) and debt type (rows).  See below a section of my code used to calculate a June year-to-date average outstanding balance. If the debt has been open for the entire period then a simple average is used in my formula. However if the debt is incurred sometime in the middle of the period I need to adjust the denominator in my formula to be the number of periods open. I'm trying to avoid a series of nested CASE statements as I have to do the calculation for each of the twelve months. Any Ideas?

See my image attachment below. The first line should be divided by 2 instead of 6 as the debt was only open for two months at the time of the report.


select
Category
Beg_bal,
Jan_bal,
Feb_bal,
Mar_bal,
Apr_bal,
May_bal,
(Beg_bal + Jan_bal + Feb_bal + Mar_bal + Apr_bal + May_bal) / 6 as ytd_Jun_avg,
from #working

Thanks!
David

average-example.JPG (28 KB) (File Type Details) 

average example

Answer : How I can simplify a series of nested case statements in a MS SQL 2005 query

use sign function

(Beg_bal + Jan_bal + Feb_bal + Mar_bal + Apr_bal + May_bal)
/  (sign(Beg_bal) + sign(Jan_bal) + sign(Feb_bal) + sign(Mar_bal) + sign(Apr_bal) + sign(May_bal))
as ytd_Jun_avg,