// gets all order IDs for the combo box
public static List <int> GetOrderIDs()
{
List <int> orderIDs = new List <int>(); // empty list of IDs
int id; // for reading
using (SqlConnection connection = NorthwindDB.GetConnection())
{
string query = "SELECT OrderID FROM Orders";
// any exception not handled here is automatically thrown to the form
// where the method was called
using (SqlCommand cmd = new SqlCommand(query, connection))
{
connection.Open();
SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
// close connection as soon as done with reading
while (reader.Read())
{
id = (int)reader["OrderID"];
orderIDs.Add(id);
}
} // command object recycled
} // connection object recycled
return(orderIDs);
}