断开式ComboBox首行插入

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.SqlClient;


namespace WindowsFormsApplication20
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            // 连接字符串
            String connStr = "Data Source=.;Initial Catalog=dbok;Persist Security Info=True;User ID=sa;Password=root123123";
            // 连接对象
            SqlConnection conn = new SqlConnection(connStr);

            // 小卡车
            String sql = "select * from sanguo";
            SqlDataAdapter adapter = new SqlDataAdapter(sql, conn);

            // 小仓库
            DataSet ds = new DataSet();

            // 小车填库
            adapter.Fill(ds, "test");

            // 新建一个行
            DataRow row = ds.Tables["test"].NewRow();
            row["name"] = "aaa";
            row["attack"] = 66;
            row["country"] = "其他";
            row["gender"] = 1;
            row["id"] = 999;

            // 把这个行插入到表中
            ds.Tables["test"].Rows.InsertAt(row, 0);

            // 关联combobox
            cbName.DataSource = ds.Tables["test"];
            cbName.DisplayMember = "name";
            cbName.ValueMember = "id";


        }

        private void button1_Click(object sender, EventArgs e)
        {
            MessageBox.Show(cbName.SelectedValue.ToString());
        }

        private void button2_Click(object sender, EventArgs e)
        {
            MessageBox.Show(comboBox1.ValueMember);
        }
    }
}