keep focus on datagrid's selected row after update

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C#

hello_ i searched it in forums and google but i couldnt sokve it.
i have a datagrid view on my form.
when I select a row and update it, how do I keep focus on the selected row after update instead of it going to the first row .
i want when i click on every row _it remain in selected state after update

this is my show button:

private void show_Click(object sender, EventArgs e)
      {
          SqlConnection con = new SqlConnection();
          con.ConnectionString = @"Data Source=MA-PC;Initial Catalog=bookstore;Integrated Security=True";
          con.Open();
          SqlCommand com = new SqlCommand();
          com.CommandType = CommandType.Text;
          com.Connection = con;
          com.CommandText = "select * from book";
          SqlDataAdapter da = new SqlDataAdapter(com);
          DataTable dt = new DataTable();
          da.Fill(dt);
          dataGridView1.DataSource = dt;
      }

this is my code:(Update)

   private void Update_click(object sender, EventArgs e)
        {
    SqlConnection con = new SqlConnection();
            con.ConnectionString = @"Data Source=MA-PC;Initial Catalog=bookstore;Integrated Security=True";
            con.Open();
            SqlCommand com = new SqlCommand();
            com.CommandType = CommandType.Text;
            com.Connection = con;
            com.CommandText = "update book set bookname=@bookname,publisher=@publisher where book_code=@book_code";
            com.Parameters.AddWithValue("@bookname", txt1.Text);
            com.Parameters.AddWithValue("@publisher", txt2.Text);
            com.Parameters.AddWithValue("@book_code",Int32.Parse( dataGridView1["book_code",dataGridView1.CurrentRow.Index].Value.ToString()));
            com.ExecuteNonQuery();
            con.Close();
            show_Click(null, null);   //for refresh
            gotoselect(); 
}

this is a function:

 public void gotoselect()
{
        1   DataGridViewRow rowToSelect = this.dataGridView1.CurrentRow;

        2   rowToSelect.Selected = true;

        3   rowToSelect.Cells[0].Selected = true;

        4   this.dataGridView1.CurrentCell = rowToSelect.Cells[0];

        5   this.dataGridView1.BeginEdit(true);
}

I changed selectionmode=cellselect and it answered, but I could not solve problem yet. Is it going to the first row again?

Please help.