Create a scalar-valued function named fnUnpaidInvoiceID that returns the InvoiceID of the earliest invoice with an unpaid balance. Test the function in the following SELECT statement: SELECT VendorName, InvoiceNumber, InvoiceDueDate, InvoiceTotal - CreditTotal - PaymentTotal AS Balance FROM Vendors JOIN Invoices ON Vendors. VendorID = Invoices. VendorID WHERE InvoiceID = dbo. fnUnpaidInvoiceID();