RetrieveSQLData.cs

CustomerID = Convert.ToInt32(CustomerIDTextBox2.Text);

            dataGridView4.Show();

            SqlConnection con = new SqlConnection(path);
            con.Open();
            SqlCommand com = new SqlCommand("Select * From InvoiceDetails where CustomerID = '" + CustomerID + "'", con);
            SqlDataAdapter sda = new SqlDataAdapter(com);
            DataTable dt = new DataTable();
            sda.Fill(dt);
            dataGridView4.DataSource = dt.DefaultView;
            con.Close();