how to select record show in gridview in asp.net

Question

private void DisplayData()

{

dataGridView1.AutoGenerateColumns = false;

con.Open();

DataTable dt = new DataTable();

adapt = new SqlDataAdapter("select Tax_ID,Tax,percentage from Tax", con);

cmd.Parameters.AddWithValue("@Tax", this.txt_tax.Text.Trim());

cmd.Parameters.AddWithValue("@percentage", this.txt_per.Text.Trim());

cmd.ExecuteNonQuery();

adapt.Fill(dt);

dataGridView1.DataSource = dt;

con.Close();

}

 

 

Tax_Id Don't show in grid view.....???