private void btnRegister_Click(object sender, EventArgs e)
        {
            if (!string.IsNullOrEmpty(txtUsername.Text) && !string.IsNullOrEmpty(txtPassword.Text) && !string.IsNullOrEmpty(txtConfirm.Text) && !string.IsNullOrEmpty(txtMobile.Text) && !string.IsNullOrEmpty(txtEmail.Text))
            {
                string constring = ConfigurationManager.ConnectionStrings["ConnData"].ConnectionString;
                SqlConnection con = new SqlConnection(constring);
                SqlCommand cmd = con.CreateCommand();
                cmd.CommandType = CommandType.Text;
                cmd.CommandText = "select Username from UserLogin where Username ='" + txtUsername.Text + "'";

                DataTable dt = new DataTable();
                SqlDataAdapter da = new SqlDataAdapter(cmd);
                da.Fill(dt);

                if (dt.Rows.Count > 0)
                {
                    MessageBox.Show("Username has been taken. Please try again.");
                    return;
                }
                else if (txtPassword.Text != txtConfirm.Text)
                {
                    MessageBox.Show("Password does not match.");
                }
                else
                {
                    registerUser();
                }
            }
            else
            {
                MessageBox.Show("Please key in your details");
                return;
            }
        }