>>

>>        public static decimal ComputeWeightDifference(int transactionHeaders_Id,PICSEntities context)
>>        {
>>            decimal emWeight = (decimal) context.EMTransactions.Where(r => (r.TransactionHeaders_Id == transactionHeaders_Id)).Sum(r => r.Weight) ?? 0;
>>            decimal? detailsWeight = 0;
>>            emWeight = (decimal?) context.EMTransactions.Where(r => (r.TransactionHeaders_Id == transactionHeaders_Id)).Sum(r => r.Weight) ?? 0;
>>            detailsWeight = context.TransactionDetails.Where(r => (r.TransactionHeaders_Id == transactionHeaders_Id)).Sum(r => r.Weight);
>>            return (decimal)(emWeight  - (decimal) (detailsWeight ?? 0);
>>        }
>>

>>I'm really puzzled by this statement:
>>

>>          decimal emWeight = context.EMTransactions.Where(r => (r.TransactionHeaders_Id == transactionHeaders_Id)).Sum(r => r.Weight) ?? 0;
>>

>>
>>It won't compile. CS0019 Operator '??' cannot be applied to operands of type 'decimal' and 'int'
>>
>>But this does :
>>
>>

>>return emWeight  - (decimal) (detailsWeight ?? 0);
>>

>>
>>So is there a way to do is in one line, or do I first need to extract the transactions and check if there are none?
>
>
>If you want null results to be treated as 0 then you could just use : Sum(r=>r.Weight ?? 0)


Viv,
I think that is worse. If the weight itself is nullable (as this expression implies) then this would compile, but would error when there is no matching records.

And thanks for the heads up the correct way to write it, regardless the underlying field is nullable or not, is:

public static decimal ComputeWeightDifference(int transactionHeaders_Id, PICSEntities context)
{
	decimal emWeight = context.EMTransactions.Where(r => r.TransactionHeaders_Id == transactionHeaders_Id).Sum(r => (decimal?)r.Weight) ?? 0;
	decimal detailsWeight = context.TransactionDetails.Where(r => r.TransactionHeaders_Id == transactionHeaders_Id).Sum(r => (decimal?)r.Weight) ?? 0;
	return emWeight - detailsWeight;
}