How to get number of rows returned to binding source

Question

Hello i have the following code based on Northwind database

   public void select_orders(String CustID)
        {
            
             string connectionString = @"Server=localConn; Initial Catalog=Northwind; Integrated Security=True";
            using (SqlConnection conn = new SqlConnection(connectionString))
            {
                SqlCommand cmd = new SqlCommand("SELECT_ORDERS", conn);
                cmd.CommandType = CommandType.StoredProcedure;
                cmd.Parameters.Add(new SqlParameter("@CustomerID", CustID));
                conn.Open();

                //Fill The DataTable From Command 
                SqlDataAdapter da = new SqlDataAdapter(cmd);
                DataTable dt = new DataTable();
                da.Fill(dt);

                //Set It To Binding Navigator
                BindingSource itmBindSource = new BindingSource();
                itmBindSource.DataSource = dt;
                itmBindNavigator.BindingSource = itmBindSource;
                itmBindNavigator.Dock = DockStyle.Bottom;

                TextBox temp_checked = new TextBox();
                temp_checked.DataBindings.Add("Text", itmBindSource, "ShipPostalCode");
                if (temp_checked.Text != null)
                    checkBox1.CheckState = System.Windows.Forms.CheckState.Checked;
                else
                    checkBox1.CheckState = System.Windows.Forms.CheckState.Unchecked;

                custID_txt.DataBindings.Add("Text", itmBindSource, "CustomerID");
                shipRegion_combo.DataBindings.Add("SelectedValue", itmBindSource, "ShipRegion");
                freight_txt.DataBindings.Add("Text", itmBindSource, "Freight");
                
                 orderID_txt.DataBindings.Add("Text", itmBindSource, "OrderID");

            }
        }

How can i check if it returns any rows? Actually i want if return rows result is 0 then all textfields would be read only.

Thank you in advance!