C#WinForm Mysql查询填充组合框帐户及其子帐户等子帐户

请帮帮我。我创建了一个windows窗体，带有一个组合框，在C#with Mysql数据库中，表名是accounthead，来自此表我只想填充特定帐户及其子帐户，例如销售a/C，并且在此表下仅填充所有子帐户

Mysql数据库表名：accounthead

人头编码人头下的人头名

   1    Purchase A/C       0
   9    Sales A/C          7
  10    Expense A/C        2
 101    Area A             9
 102    Area B             9
 103    Salesman 1       101
 104    Salesman 2       101
 105    Salesman 3       102
 106    Salesman 4       102


    void BindHeadName()
    {   
        string ConnectionString = Properties.Settings.Default.CurConnStr;
        using (MySqlConnection con = new MySqlConnection(ConnectionString))
            {
                string query = "Select * from accounthead ORDER BY HeadName ASC";
                MySqlCommand cmd = new MySqlCommand(query, con);
                con.Open();
                
                MySqlDataReader dr = cmd.ExecuteReader();
                while (dr.Read())
                    {
                        string gname = dr.GetString("HeadName");
                        ComboBox.Items.Add(gname);
                    }
            }
    }