dataset更新数据库不成功问题？？？

我通过代码将dataset保存至数据库中，但是我打开数据库（.mdb格式的)却还是原来的数据，这是怎么回事？
代码：

 public Form1()

        {

            InitializeComponent();

           

        }

        public static DataSet ds;

        public static DataRow[] dr;

        public static OleDbDataAdapter da;

        public static int i = 0;

        public static int n = 1;





        //更新数据

        public void updategvd()

        {



            dgv.DataSource = ds.Tables[0];

        }





        //获得textbox中内容





        public string[] textGet()

        {

            string[] str=new string[6];

            str[0] = Name.Text.ToString(); str[1] = Sex.Text.ToString(); str[2] = HomeTel.Text.ToString();

            str[3] = OfficeTel.Text.ToString(); str[4] = Mark.Text.ToString();

            return str;

        }

        private void Form1_Load(object sender, EventArgs e)

        {

            // TODO:  这行代码将数据加载到表“telephoneDataSet.telephoneinfo”中。您可以根据需要移动或删除它。

            this.telephoneinfoTableAdapter.Fill(this.telephoneDataSet.telephoneinfo);//自动添加？？

            enter form = new enter();

            form.ShowDialog();

            if (enter.flag == 0)

            {

                this.Close();

            }

            dgv.DataSource = bandsource().Tables["phone"];

        }

        public DataSet bandsource()

        {

            string str = "provider=Microsoft.Jet.OLEDB.4.0; data Source=telephone.mdb; Persist Security Info=False";

            OleDbConnection conn = new OleDbConnection(str);

            ds = new DataSet();

            try

            {

                conn.Open();

                string sqlstr = "select telephoneinfo.PersonID as 自动编号,telephoneinfo.Name as 姓名,telephoneinfo.Sex as 性别,telephoneinfo.OfficeTel as 办公室电话,telephoneinfo.HomeTel as 家庭电话,telephoneinfo.Mark as 备注 from telephoneinfo order by PersonID";

                da = new OleDbDataAdapter(sqlstr, conn);

                da.Fill(ds, "phone");

            }

            catch(Exception e)

            {

                MessageBox.Show(e.Message);

            }

            finally

            {

                conn.Close();

            }

            return ds;

        }

 private void save_Click(object sender, EventArgs e)

        {

            OleDbCommandBuilder builder = new OleDbCommandBuilder(da);

            da.Update(ds, "phone");

            ds.AcceptChanges();

        }



        private void updateData_Click(object sender, EventArgs e)

        {

            ds.Clear();

            da.Fill(ds, "phone");

            dgv.DataSource = ds.Tables["phone"]; 

        }

其中我通过update来更新数据dataset是显示的是修改之后的结果，但是当我打开数据库时，发现数据并没有更新。