Is it safe to use SUM() without ISNULL()

Question

I am trying to hence the performance of an SP. I have a doubt in my mind about SUM and ISNULL. When I sum up a column, should I use ISNULL? Is it SAFE to use SUM() without ISNUL

Answer 1

Its not mandatory to use NULL and COALESCE while doing SUM because SUM always ignore null values.

Refer the link : https://msdn.microsoft.com/en-IN/library/ms187810.aspx for more info.