//home button
        private void button2_Click(object sender, EventArgs e)
        {
            Faculty_homepage fhp = new Faculty_homepage(s1);

            fhp.Show();
            this.Hide();
        }
        //onclick of button login and validating
        private void button1_Click(object sender, EventArgs e)
        {
            if (comboBox1.Text == "student")
            {
                try
                {
                    String           oradb = "Data Source=DESKTOP-K6AG53J;Persist Security Info=True;User ID=system;Password=student;";
                    OracleConnection conn  = new OracleConnection(oradb);
                    conn.Open();
                    OracleCommand comm = new OracleCommand();
                    comm.CommandText = "select * from student where id = " + textBox1.Text;
                    comm.CommandType = CommandType.Text;
                    DataSet           ds = new DataSet();
                    OracleDataAdapter da = new OracleDataAdapter(comm.CommandText, conn);
                    da.Fill(ds, "Tbl_student");
                    DataTable dt = ds.Tables["Tbl_student"];
                    int       t1 = dt.Rows.Count;
                    DataRow   dr = dt.Rows[i];
                    if (t1 != 0)
                    {
                        ID       = dr["ID"].ToString();
                        fname    = dr["FNAME"].ToString();
                        lname    = dr["lNAME"].ToString();
                        dob      = dr["dob"].ToString();
                        sex      = dr["SEX"].ToString();
                        email    = dr["EMAIL"].ToString();
                        contact  = dr["contact_no"].ToString();
                        fa_name  = dr["father_name"].ToString();
                        address  = dr["Address"].ToString();
                        password = dr["password"].ToString();
                        p_c      = dr["parent_contact"].ToString();


                        conn.Close();
                        //validating credintials
                        if (textBox1.Text == ID && textBox2.Text == password)
                        {
                            homepage hp = new homepage(textBox1.Text);
                            hp.Show();
                            this.Hide();
                        }
                        //wrong credintials
                        else
                        {
                            label5.Text = "wrong credentials!!";
                        }
                    }
                }

                catch (IndexOutOfRangeException ex)
                {
                    MessageBox.Show("Invalid Details!");
                }
            }
            else if (comboBox1.Text == "faculty")
            {
                try
                {
                    String           oradb = "Data Source=DESKTOP-K6AG53J;Persist Security Info=True;User ID=system;Password=student;";
                    OracleConnection conn  = new OracleConnection(oradb);
                    conn.Open();
                    OracleCommand comm = new OracleCommand();
                    comm.CommandText = "select * from faculty where id = " + textBox1.Text;
                    comm.CommandType = CommandType.Text;
                    DataSet           ds = new DataSet();
                    OracleDataAdapter da = new OracleDataAdapter(comm.CommandText, conn);
                    da.Fill(ds, "Tbl_faculty");
                    DataTable dt = ds.Tables["Tbl_faculty"];
                    int       t2 = dt.Rows.Count;
                    DataRow   dr = dt.Rows[i];
                    if (t2 != 0)
                    {
                        ID    = dr["ID"].ToString();
                        fname = dr["FNAME"].ToString();
                        lname = dr["lNAME"].ToString();
                        dob   = dr["dob"].ToString();
                        sex   = dr["SEX"].ToString();
                        //email = dr["EMAIL"].ToString();
                        contact  = dr["contact_no"].ToString();
                        dept     = dr["dept"].ToString();
                        address  = dr["Address"].ToString();
                        password = dr["password"].ToString();
                        // p_c = dr["parent_contact"].ToString();


                        conn.Close();

                        //validating credintials
                        if (textBox1.Text == ID && textBox2.Text == password)
                        {
                            Faculty_homepage fhp = new Faculty_homepage(textBox1.Text);
                            fhp.Show();
                            this.Hide();
                        }
                        //wrong credintials
                        else
                        {
                            label5.Text = "wrong credentials!!";
                        }
                    }
                }

                catch (IndexOutOfRangeException ex)
                {
                    MessageBox.Show("Invalid Details!");
                }
            }
        }