C# มีปัญหากับการวน size ของ datagridview เพื่อที่จะเอาค่ามาใช้งาน

private void dgvShowReceive_CellClick(object sender, DataGridViewCellEventArgs e)
        {
            if (e.ColumnIndex == 0)
            {
                if (Convert.ToBoolean(dgvShowReceive.Rows[e.RowIndex].Cells["Select"].Value) == false)
                {
                    dgvShowReceive.Rows[e.RowIndex].Cells["Select"].Value = true;
                    DialogResult result = MessageBox.Show("คุณต้องบันทึกใช่ไหม ?", "ยืนยันการรับ", MessageBoxButtons.YesNo);
                    if (result == DialogResult.No)
                    {
                        dgvShowReceive.Rows[e.RowIndex].Cells["Select"].Value = false;
                    }
                    if (result == DialogResult.Yes)
                    {
                        
                        for (int i = 0; i <= dgvShowReceive.Rows.Count - 1; i++)
                        {
                            string id = dgvShowReceive.Rows[e.RowIndex].Cells[1].Value.ToString();
                            string keepItemID = dgvShowReceive.Rows[e.RowIndex].Cells[9].Value.ToString();

                            tr = Conn.BeginTransaction();
                            sb = new StringBuilder();
                            sb.Append("UPDATE tblOrderNormalTrn SET OrnStatus=@OrnStatus WHERE OrdID='" + id + "' AND ItemID='" + keepItemID + "'");
                            string sqlup = sb.ToString();

                            com.CommandText = sqlup;
                            com.CommandType = CommandType.Text;
                            com.Connection = Conn;
                            com.Transaction = tr;
                            com.Parameters.Clear();
                            com.Parameters.Add("@OrnStatus", SqlDbType.Bit).Value = 1;
                            com.ExecuteNonQuery();
                            tr.Commit();

                            MessageBox.Show("บันทึกช้อมูลเสร็จสมบูรณ์ ", "ข้อความ", MessageBoxButtons.OK, MessageBoxIcon.Information);

                            ShowDataMember();
                            ShowdgvShowReceive();
                            return;
                        }
                    }

                }
            }
        }