DataGridView 绑定自动刷新的有关问题

DataGridView 绑定自动刷新的问题

      private void bind()

        {

            string str = "select * from department";


            {

                string connstr = frmMain.GetConnString();

                SqlConnection conn = new SqlConnection(connstr);

                conn.Open();

                da = new SqlDataAdapter(str, conn);

                da.Fill(ds);

                while (dataGridViewX1.Rows.Count - 1 > 0)

                {

                    dataGridViewX1.Rows.Remove(dataGridViewX1.Rows[0]);

                }


                if (dataGridViewX1.Columns.Contains("deptid"))

                {

                    dataGridViewX1.Columns.Remove("deptid");

                    dataGridViewX1.Columns.Remove("deptname");

                    

                }


                dataGridViewX1.Visible = true;

                dataGridViewX1.Columns.Clear();

                dataGridViewX1.Columns.Add("deptid", "办事机构ID");

                dataGridViewX1.Columns["deptid"].DataPropertyName = "deptid";

                dataGridViewX1.Columns.Add("deptname", "办事机构名称");

                dataGridViewX1.Columns["deptname"].DataPropertyName = "deptname";

                dataGridViewX1.DataSource = ds.Tables[0];

                dataGridViewX1.Refresh();

                conn.Close();

            }

        }

这段代码调用的时候，我想用来自动刷新DataGridView里的数据，重新从数据库读一次。但这样似乎没啥效果。谁能给一个DataSet自动刷新的例子啊？
------解决方案--------------------
     DataTable dt=new DataTable();
     da.fill(dt);
     dataGridViewX1.DataSource= dt;