//fill the order combobox datasource with the data from database by using dbcontext private void Form1_Load(object sender, EventArgs e) { //display orders details and order when formloads from the database. using (OrdersDataContext db = new OrdersDataContext()) //connect to db { orderIDComboBox.DataSource = from ord in db.Orders //fill the combobox i.e datasource with order id's from orders table orderby ord.OrderID select ord.OrderID; } }