private void button2_Click(object sender, EventArgs e)
        {
            SqlConnection  con = new SqlConnection(@"Data Source = (LocalDB)\MSSQLLocalDB; AttachDbFilename = ""C:\Users\hassan hassan\Documents\Visual Studio 2015\Projects\LibrarySystem\LibrarySystem\LibrarySystemDB.mdf""; Integrated Security = True; Connect Timeout = 30");
            SqlDataAdapter adp = new SqlDataAdapter("Select Email , Password , Type From Users", con);
            DataTable      tbl = new DataTable();

            adp.Fill(tbl);
            SqlCommand cmd = new SqlCommand("", con);

            con.Open();
            cmd.CommandText = "SELECT COUNT(*) FROM Users";
            Int32 count = (Int32)cmd.ExecuteScalar();

            try
            {
                for (int i = 0; i < count; i++)
                {
                    if (tbl.Rows[i][0].ToString() == textBox1.Text && tbl.Rows[i][1].ToString() == textBox2.Text)
                    {
                        if (tbl.Rows[i][2].ToString() == "True")
                        {
                            this.Hide();
                            AdminPage open = new AdminPage();
                            open.Show();
                        }
                        else
                        {
                            this.Hide();
                            Main open = new Main();
                            open.Show();
                        }
                        return;
                    }
                }
                MessageBox.Show("invalid email / Password please enter the correct email / Password");
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message.ToString());
            }
        }