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POSum in Linq to Sql not returning a value
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  1. POSum in Linq to Sql not returning a value
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    copied!<p>I'm looking for a query to return the sum of all payments against an invoice ID - however, if there are no payments noted, the query below returns null. Is there any way of it returning 0 instead of null? I've tried adding ?? 0 at the end, but get the message <code>Operator ?? cannot be applied to operands of type decimal and int</code></p> <p>AmountAllocated is of type Decimal:</p> <pre><code>public decimal AmountAllocated { get; set; } </code></pre> <p>Thanks, Mark</p> <p>The following returns null for Sum when there are no payment rows found:</p> <pre><code> var invoiceVM = from i in db.Invoices where i.UserName==userName select new NewInvoiceViewModel { InvoiceId = i.InvoiceId, SumPayments = db.PaymentInvoices.Where(pi =&gt; pi.InvoiceId == i.InvoiceId) .Select(pi =&gt; pi.AmountAllocated).Sum() }; </code></pre> <p>The following results in the <code>Operator ?? cannot be applied to operands of type decimal and int</code> error:</p> <pre><code> var invoiceVM = from i in db.Invoices where i.UserName==userName select new NewInvoiceViewModel { InvoiceId = i.InvoiceId, SumPayments = db.PaymentInvoices.Where(pi =&gt; pi.InvoiceId == i.InvoiceId) .Sum(pi =&gt; pi.AmountAllocated) ?? 0 }; </code></pre> <p>If there have been payments made, then AmountAllocated correctly returns the sum of those payments - just it returns null if there are no payment rows found.</p> <p>You can see from the screenshot below, the first record has a payment, and shows correct as 10 (decimal) - the second record has no payments, and shows as null (decimal).</p> <p><img src="https://i.stack.imgur.com/mRklk.png" alt="screenshot"></p>
 

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