public void UpdateCustomerInvoice(Customer_Invoice customerInvoice)
 {
     context.Entry(customerInvoice).State = EntityState.Modified;
 }
 public void InsertCustomerInvoice(Customer_Invoice customerInvoice)
 {
     int id = context.Database.SqlQuery<int>("GetCustomerInvoiceMaxID").Single() + 1;
     context.Customer_Invoice.Add(customerInvoice);
 }