how to do different permutation combinations with two comboboxes values?

public void all()
{
    SqlCommand cm1 = new SqlCommand("select * from traintime where No BETWEEN 1 AND 20", con);
    DataTable dth = new DataTable();
    SqlDataAdapter da = new SqlDataAdapter(cm1);
    da.Fill(dth);
    dataGridView2.DataSource = dth;
}
private void button1_Click(object sender, EventArgs e)
{
    if (comboBox1.SelectedIndex == 0 || comboBox1.SelectedIndex == 1 ||
        comboBox1.SelectedIndex == 2 || comboBox1.SelectedIndex == 3 ||
        comboBox1.SelectedIndex == 4 && comboBox2.SelectedIndex==5)
    {
        all();
    }
    else if (comboBox1.SelectedIndex == 0 ||
        comboBox1.SelectedIndex == 1 ||
        comboBox1.SelectedIndex == 2 ||
        comboBox1.SelectedIndex == 3 ||
        comboBox1.SelectedIndex == 4 ||
        comboBox1.SelectedIndex == 5 && comboBox2.SelectedIndex == 6)
    {
        SqlCommand cm1 = new SqlCommand("select * from traintime where TrainNo=11026", con);
        DataTable dth = new DataTable();
        SqlDataAdapter da = new SqlDataAdapter(cm1);
        da.Fill(dth);
        dataGridView2.DataSource = dth;
    }