private void btnEditItems_Click(object sender, EventArgs e)
        {
            try
            {
                string warehouse, supplier, date;
                warehouse = cbWarehouses.Text;
                supplier  = cbSuppliers.Text;
                date      = dtpDate.Text;

                if (!string.IsNullOrEmpty(txtOrderNumber.Text))
                {
                    int            id    = int.Parse(txtOrderNumber.Text);
                    SupplyingOrder order = (from c in ent.SupplyingOrders
                                            where c.number == id
                                            select c).FirstOrDefault();

                    obj = new SupplyOrderInfo(order.number);
                    obj.Show();
                }
                else
                {
                    MessageBox.Show("Error!\n" +
                                    "the Order you are trying to update doesn't exist.\n" +
                                    "hint: try \"New\" instaed");
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
        private void btnNew_Click(object sender, EventArgs e)
        {
            try
            {
                string warehouse, supplier, date;
                warehouse = cbWarehouses.Text;
                supplier  = cbSuppliers.Text;
                date      = dtpDate.Text;

                if (!string.IsNullOrEmpty(warehouse) && !string.IsNullOrEmpty(supplier) && !string.IsNullOrEmpty(date))
                {
                    int warehouseId = (from w in ent.Wharehouses
                                       where w.name == warehouse
                                       select w.ID).FirstOrDefault();

                    int supplierId = (from s in ent.Providers
                                      where s.name == supplier
                                      select s.id).FirstOrDefault();
                    var            d     = Convert.ToDateTime(date);
                    SupplyingOrder order = new SupplyingOrder
                    {
                        supplier_id  = supplierId,
                        warehouse_id = warehouseId,
                        date         = d
                    };
                    ent.SupplyingOrders.Add(order);
                    ent.SaveChanges();
                    MessageBox.Show("Order added!\n", "", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    //SupplingOrders_Load(sender, e);
                    obj = new SupplyOrderInfo(order.number);
                    obj.Show();
                }
                else
                {
                    MessageBox.Show("All Fields Required!", "", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }