private void textBox5_TextChanged(object sender, EventArgs e)
{
    objConn1.Open();
    int nQty = 0;
    int nActualQty = Convert.ToInt32(textBox5.Text.ToString());
    string sql3 = "select qty from dbo.RateMouldQuantity where ratechart= '" + comboBox5.SelectedValue.ToString() + "'";
    SqlCommand com = new SqlCommand(sql3, objConn1);
    SqlDataReader objQty = com.ExecuteReader();
    if (objQty.Read())
    {
        nQty = Convert.ToInt32(objQty["Qty"]);
    }
    if (nQty < nActualQty)
    {
        MessageBox.Show("Qty is greater");
    }
    objConn1.Close();
}