>>>In his code he doesn't need ?? operator, I believe.
>>
>>He does.
>
>You're right. For a minute I thought SUM will produce 0 when no results are matching, but I ran a test in SQL Server and got NULL, so that answers my original incorrect thought.

Got you, in VFP too (in 7.0?) it was also changed to return NULL and people complained at that time as I remember. Here the real problem is ?? with two non null values is an exception for C# (why in the world I don't know, that is MS after all).