5. 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...

5. 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();