OleDbDataAdapte.Update(DataTable)存不住数据，每次重新打开程序数据就又恢复了

这是代码

OleDbConnection myConnection5;
        OleDbDataAdapter myDA5;
        DataTable myDT5;
        OleDbCommandBuilder myDC;
        OleDbCommand myC;
        private void FrmScoreInput_Load(object sender, EventArgs e)
        {
            myConnection5 = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=\".\\XKDB.mdb\"");
            myDA5 = new OleDbDataAdapter("Select * from ELECTIVE where StudentID=''", myConnection5);
           // myC = new OleDbCommand("Select * from ELECTIVE where StudentID=''", myConnection5);
            myDC = new OleDbCommandBuilder(myDA5);
          //  myDA5.SelectCommand.Parameters.Clear();
           // myDA5.SelectCommand.Parameters.Add("@StudentID", System.Data.OleDb.OleDbType.Char, 10);
          //  myDA5.SelectCommand.Parameters["@studentID"].Value = cboCouseList.Text;


            myDT5 = new System.Data.DataTable();
            myDA5.Fill(myDT5);
            dgvStudents.DataSource = myDT5;

            lbStuID.DataBindings.Clear();
            lbStuName.DataBindings.Clear();
            lbClass.DataBindings.Clear();
            txtScore.DataBindings.Clear();
            lbStuID.DataBindings.Add("Text", myDT5, "StudentID");
            lbStuName.DataBindings.Add("Text", myDT5, "StudentName");
            lbClass.DataBindings.Add("Text", myDT5, "ClassID");
            txtScore.DataBindings.Add("Text", myDT5, "SCORE");

private void tlbLoadData_Click(object sender, EventArgs e)
        {

            if (cboCouseList.Text == "") { MessageBox.Show("请先选择课程！！！", "警告！", MessageBoxButtons.OK,MessageBoxIcon.Information); }
             else
             {
                 myDT5.Clear();
                 myDA5.SelectCommand.CommandText = "Select * from ELECTIVE where COUSEID='" + cboCouseList.Text.Substring(0, 4) + "'";
                 myDA5.Fill(myDT5);
                 //myDT5.Rows[4].BeginEdit();
                 txtScore.Focus();
             }
        }

private void tlbStatic_Click(object sender, EventArgs e)
        {
            if (cboCouseList.Text == "") { MessageBox.Show("请先加载数据！！！", "警告！", MessageBoxButtons.OK, MessageBoxIcon.Information); }
            else
            {
                // myDT5.Clear();
                myDA5.SelectCommand.CommandText = "Select count(StudentID) from ELECTIVE where SCORE<>0 and COUSEID='" + cboCouseList.Text.Substring(0, 4) + "'";
                myConnection5.Open();
                string a = myDA5.SelectCommand.ExecuteScalar().ToString();
                myConnection5.Close();

                // myDT5.Clear();
                myDA5.SelectCommand.CommandText = "Select count(StudentID) from ELECTIVE where SCORE=0 and COUSEID='" + cboCouseList.Text.Substring(0, 4) + "'";
                myConnection5.Open();
                string b = myDA5.SelectCommand.ExecuteScalar().ToString();
                myConnection5.Close();

                MessageBox.Show("已录入成绩" + a + "人\n零分或未录入成绩" + b + "人", "统计结果！", MessageBoxButtons.OK, MessageBoxIcon.Information);

            }

        }

  private void tlbSubmitAll_Click(object sender, EventArgs e)
        {
            if (cboCouseList.Text == "") { MessageBox.Show("请先加载数据！！！", "警告！", MessageBoxButtons.OK, MessageBoxIcon.Information); }
            else
            {
               // myDA5.UpdateCommand = myDC.GetUpdateCommand();

                myDT5.GetChanges();
                myConnection5.Open();

                myDA5.Update(myDT5);
                myConnection5.Close();
                myDT5.AcceptChanges();
                MessageBox.Show("成绩提交成功！！","提示！" ,MessageBoxButtons.OK, MessageBoxIcon.Information);
              //  myDA5.SelectCommand.CommandText = "Select * from ELECTIVE where COUSEID='" + cboCouseList.Text.Substring(0, 4) + "'";
               // myDA5.Fill(myDT5);
            }
        } --------------------编程问答-------------------- 问题已解决。。。
把数据文件设置成不要复制就行了。。

补充：.NET技术 ,  C#