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

Yes its safe . You can use Sum without handling NULL Value. You can also check that.

You can use like that also.

ISNULL(SUM(COL1),0).

Returns the sum of all the values, or only the DISTINCT values, in the expression. SUM can be used with numeric columns only. Null values are ignored.

For Reference : https://msdn.microsoft.com/en-IN/library/ms187810.aspx