filling gridview in button click

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C#

C#4.0

In button click am filling gridview using datatable as datasource,and also am adding button in cell of gridview.

here the problem is:

when i click button
1) gridview data should be refreshed.
gridview,Refresh();
is not refreshing .

2)
i can change the values of gridview ,and click the button in corresponding row, that row should be updatd in datsbase also

<pre lang="c#"> private void btnedittxok_Click(object sender, EventArgs e)
        {
//            this.dataGridView1.EndEdit();

//this.dataGridView1.Refresh();
           
            if (txtedittxcustomer.Text != "")
            {
                String date1 = dateTimePicker1.Text;
                String[] date = Regex.Split(date1, "[/: ]");
                StringBuilder sb = new StringBuilder();
                sb.Append(date[2]);
                sb.Append("-");
                sb.Append(date[0]);
                sb.Append("-");
                sb.Append(date[1]);
                String fromdate = sb.ToString();


                String date2 = dateTimePicker2.Text;
                String[] date3 = Regex.Split(date2, "[/: ]");
                StringBuilder sb1 = new StringBuilder();
                sb1.Append(date3[2]);
                sb1.Append("-");
                sb1.Append(date3[0]);
                sb1.Append("-");
                sb1.Append(date3[1]);
                String todate = sb1.ToString();

                String customer = txtedittxcustomer.Text;
                String card = txtedittxcard.Text;


                using (MySqlConnection con = new MySqlConnection(ConnectionString))
                {
                    query = "select * from transaction where DATE(paid_date)BETWEEN '" + fromdate + "'AND'" + todate + "' AND customer_id='" + customer + "' ";
                    con.Open();
                    da = new MySqlDataAdapter(query, con);

                   //da.Fill(ds);
                    da.Fill(dt);
                    dataGridView1.DataSource = dt;
                    int dtRows = dt.Rows.Count;
                    if (dtRows == 0)
                    {
                        MessageBox.Show("No Records");
                    }
                    else
                        groupBox2.Visible = true;
                    //dataGridView1.DataMember = ds.Tables[0].ToString();
                    DataGridViewButtonColumn btnEdit = new DataGridViewButtonColumn();
                    dataGridView1.Columns.Add(btnEdit);
                    btnEdit.HeaderText = "Edit";
                    btnEdit.Text = "Edit";
                    btnEdit.Name = "btnEdit";
                    btnEdit.UseColumnTextForButtonValue = true;

                }
              

            }
            else
                MessageBox.Show("Please enter Customer ID");
        }