private void Button1_Click(object sender, EventArgs e)
        {
            string query = "select * from administrator where username = '******' and password = '******'";

            try
            {
                conn.Open();
                OracleCommand     cmd = new OracleCommand(query, conn);
                OracleDataAdapter oda = new OracleDataAdapter(query, conn);
                DataTable         dt  = new DataTable();
                oda.Fill(dt);
                if (dt.Rows.Count > 0)
                {
                    AdminPanel ap = new AdminPanel();
                    this.Hide();
                    ap.ShowDialog();
                    this.Close();
                }
                else
                {
                    MessageBox.Show("Please enter username and password correctly", "warning", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                }
                conn.Close();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }
        }
        private void BackToAdminPanelToolStripMenuItem_Click(object sender, EventArgs e)
        {
            AdminPanel ap = new AdminPanel();

            this.Hide();
            ap.ShowDialog();
            this.Close();
        }