自动完成整个数据网格行

Question

我想用数据库中的数据自动完成一个数据网格单元，并在选择项目后显示从数据库到该数据网格的多个行项目（具有那些标题）。目前，我只能从数据库中搜索填充了数据网格的唯一单元格的项目。我怎样才能达到我的解释？ 我当前的代码如下：

//auto complete item name on datagrid
private void dataGridView1_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
{
    try
    {
        if (dataGridView1.CurrentCell.ColumnIndex==0)
        {
            SqlDataReader dreader;
            SqlConnection conn = new SqlConnection(connectionstring);
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = conn;
            cmd.CommandType = CommandType.Text;
            AutoCompleteStringCollection autocomplete = new AutoCompleteStringCollection();
            cmd.CommandText = "SELECT ItemName,ItemCode,Units,MainGroup,SubGroup from StockItems";
            conn.Open();
            dreader = cmd.ExecuteReader();
            if (dreader.HasRows == true)
            {
                while (dreader.Read())
                    autocomplete.Add(dreader["ItemName"].ToString());
            }
            else
            {
                MessageBox.Show("Data not Found");
            }
            dreader.Close();
            TextBox txtBusID = e.Control as TextBox;
            if (txtBusID != null)
            {
                txtBusID.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
                txtBusID.AutoCompleteCustomSource = autocomplete;
                txtBusID.AutoCompleteSource = AutoCompleteSource.CustomSource;
            }
        }
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }

}