How do I get values 12.0 save and displayed in data grid view

private void button1_Click(object sender, EventArgs e)
    {
        if (comboBoxstaff.Text == string.Empty)
        {
            MessageBox.Show("Please Select gaugeman");  // not to let thecombobox empty
            return;
        }
        else if (comboBoxcompondrubber.Text == string.Empty)
        {
            MessageBox.Show("Please Select Compond Rubber");// not to let thecombobox empty
            return;

        }
        else if (textBox1.Text == string.Empty)
        {
            MessageBox.Show("Please Key in W.S thickness");// not to let thetextbox empty
            return;

        }
        else if (textBox2.Text == string.Empty)
        {
            MessageBox.Show("Please Key in G.S thickness");// not to let thecombobox empty

        }
        SQLiteConnection insertsess = new SQLiteConnection("Data Source=|DataDirectory|\\test1db");
        string insert12 = "INSERT INTO thickness (GaugeMan,Dateandtime, CompondRubber,GSthickness,WSthicknes) VALUES ('" + comboBoxstaff.Text + "','" + label2.Text + "', '" + comboBoxcompondrubber.Text + "', '" + textBox2.Text + "', '" + textBox1.Text + "')";   //insert statment
        SQLiteCommand ins1 = new SQLiteCommand(insert12, insertsess);
        insertsess.Open();
        ins1.ExecuteNonQuery();
        MessageBox.Show("Data had been saved");// showed when the message is being saved

        SQLiteConnection sesscheck = new SQLiteConnection("Data Source=|DataDirectory|\\test1db");
        SQLiteCommand chk1;
        chk1 = sesscheck.CreateCommand();
        chk1.CommandText = "SELECT GaugeMan,Dateandtime, CompondRubber,GSthickness,WSthicknes FROM thickness WHERE CompondRubber = '" + comboBoxcompondrubber.Text.Trim() + "'";
       sesscheck.Open();
        DataTable thicknessTable = new DataTable();
        //DataTable thicknessTable = new DataTable();
        SQLiteDataReader reader = chk1.ExecuteReader();
        thicknessTable.Load(reader);
        //SQLiteDataReader reader1 = chk2.ExecuteReader();
        //thicknessTable.Load(reader1);
        sesscheck.Close();

        dt = new DataTable();
        sda.Fill(dt);
        dataGridView1.DataSource = dt;

    }