Question

So in this example I m trying to return a NULL instead of an empty nvarchar for element2 and element3. I can t seem to find an answer to this anywhere, or if it s even possible. I know I can check .exists() with a nullif of Case/When, but I d rather not make that check for the sake of performance.

 WqlEventQuery query = new WqlEventQuery();
        query.EventClassName = "__InstanceCreationEvent";
        query.Condition = "TargetInstance ISA  Win32_NTLogEvent ";
        query.GroupWithinInterval = new TimeSpan(0, 0, 10);
        System.Collections.Specialized.StringCollection collection =
            new System.Collections.Specialized.StringCollection();
        collection.Add("TargetInstance.SourceName");
        query.GroupByPropertyList = collection;
        query.HavingCondition = "NumberOfEvents > 25";

Answer 1

I m not sure what language you are writing in from your question, but SQL Server has a NullIf(val, CheckValue) function. If you can include that in the sql you pass to the server that should do the trick:

   Select NullIf(element2,   )

will return a null if element2 is equal to an empty string ( )

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