private void btn_Login_Click(object sender, EventArgs e)
        {
            var users = db.getProductsName("usuarios");

            /*frmPaginaInicial pagina = new frmPaginaInicial();
             * pagina.ShowDialog();*/

            for (int i = 0; i < users.Count; i++)
            {
                if (textBox1.Text == users[i] && textBox2.Text == users[i + 1])
                {
                    textBox1.Text = "";
                    textBox2.Text = "";

                    frmPaginaInicial pagina = new frmPaginaInicial();
                    pagina.ShowDialog();

                    return;
                }
            }

            MessageBox.Show("Login ou senha invalidos.");
            textBox1.Text = "";
            textBox2.Text = "";
        }
        private void btn_Back_Click(object sender, EventArgs e)
        {
            frmPaginaInicial frmPaginaInicial = new frmPaginaInicial();

            frmPaginaInicial.ShowDialog();
        }