mdv 9731 (1/28/2011)
I do not agree that the answer is right.Think it is supposed to be 0.
the standard deviation s (sigma) is the square root of the average value of (X - ยต)2.
Which means s = sqrt(((1-1)^2)/1) = 0
Or in other words std. deviation equals sqrt of (population-avarage) sq / number of population values
Please correct me if im wrong on the formula it has been a while since i used my statistics ๐
Even if your statistics say it is 0, SQL Server returns NULL, so the answer is still correct.
You can verify it by running the query in SQL Server Management Studio.
Need an answer? No, you need a question
My blog at https://sqlkover.com.
MCSE Business Intelligence - Microsoft Data Platform MVP