private void button10_Click(object sender, EventArgs e)
        {
            Boolean isEqual = true;
            for (int i = 0; i < dataGridView2.Rows.Count; i++)
                
            {

                if (!dataGridView2.Rows[i].Cells[2].Value.ToString().Equals(dataGridView3.Rows[i].Cells[2].Value.ToString())) 
                {
                    isEqual = false;
                    break;
                }
            }
            MessageBox.Show((isEqual) ? "Равно" : "Неравно");
        }

conn = new OracleConnection(String.Format("data Source={0};Persist Security Info=True;User ID={1}; password={2}", names, login, pwd));
                        conn.Open();

                        int i;
                        for (i = 0; i < this.dataGridView2.Rows.Count; i++)
                        {
                            string sql = string.Format("update TEST.PPOM_USER set pstatus = {0}, plicense_level = {1} where puser_id='{2}'", dataGridView2.Rows[i].Cells[2].Value, dataGridView2.Rows[i].Cells[3].Value, dataGridView2.Rows[i].Cells[0].Value);
                            cmd = new OracleCommand(sql, conn);
                            cmd.ExecuteNonQuery();
                            
                        }
                        conn.Close();

                        for (i = 0; i < this.dataGridView2.Rows.Count; i++)
                        {
                            if (строка i изменилась в процессе работы программы) {
                                ...
                                cmd.ExecuteNonQuery();
                            }
                        }