Updating database table from DataGridView in C#

I am trying to update my database rows from the DataGridView using this code:

private void button2_Click(object sender, EventArgs e)
 {
     foreach (GridViewRow dr in dataGridView1.Rows)
     {
         string constring = "Data Source = localhost; port = 3306; username = root; password = 0159";
         string Query = "Update TopShineDB.Table1 set Time = '" + dr.Cells[0].Text + "', CarColorNumber = '" + dr.Cells[1].Text + "', Interior = '" + dr.Cells[2].Text + "', Exterior = '" + dr.Cells[3].Text + "', CPlastic = '" + dr.Cells[4].Text + "', MPlastic = '" + dr.Cells[5].Text + "', SPlastic = '" + dr.Cells[6].Text + "', PlasticB = '" + dr.Cells[7].Text + "', WashExt = '" + dr.Cells[8].Text + "', WashEng = '" + dr.Cells[9].Text + "', WashTrunk = '" + dr.Cells[10].Text + "', WashSeats = '" + dr.Cells[11].Text + "', SeatsRmv = '" + dr.Cells[12].Text + "', SeatsFit = '" + dr.Cells[13].Text + "', Notes = '" + dr.Cells[14].Text + "', where Time = '" + dr.Cells[0].Text + "' ;";  
         MySqlConnection conn = new MySqlConnection(constring);
         MySqlCommand command = new MySqlCommand(Query, conn);
         MySqlDataReader myReader;

         try
         {
             conn.Open();
             myReader = command.ExecuteReader();
             MessageBox.Show("Table Successfully Updated");
             while (myReader.Read())
             {

             }
         }
         catch (Exception ex)
         {
              MessageBox.Show(ex.Message);
         }
     }
 }

But I ended up getting this error:

{"Unable to cast object of type 'System.Windows.Forms.DataGridViewRow' to type 'System.Web.UI.WebControls.GridViewRow'."}