help please in grid view selection change index

protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)

// int index = GridView1.SelectedIndex;

int id = (int)GridView1.SelectedDataKey.Values["Car_id"];

// Label1.Text=id.ToString();

string connectionString = (string)ConfigurationSettings.AppSettings["dbconnectionstr"];

OleDbConnection conn = new OleDbConnection(connectionString);

string commandstring = "Select * from Rates where Car_id=" + id;

OleDbCommand cmnon = new OleDbCommand(commandstring, conn);

OleDbDataReader rd = cmnon.ExecuteReader();

while (rd.Read())

Label2.Text = rd["Car_Name"].ToString();

int rent, tot = 0;

DateTime start = DateTime.Parse(PreviousPage.Datestart);

DateTime end = DateTime.Parse(PreviousPage.Dateend);

int totdays = (end - start).Days + 1;

if (totdays <= 1)

lbhire.Text = "Sorry start date can't be greater then end date for same month";

else

lbhire.Text = Convert.ToString(totdays);

if (totdays >= 2 && totdays <= 6)

rent = Convert.ToInt32(rd["2_6DaysLowSeason"].ToString());

else if (totdays >= 7 && totdays <= 13)

rent = Convert.ToInt32(rd["7_13DaysLowSeason"].ToString());

else

rent = Convert.ToInt32(rd["14+DaysLowSeason"].ToString());

// Label8.Text=rd["VAT%"].ToString();