How can we load multiple tables in a Dataset

Imports System.Data.SqlClient

Public Class Form1

    Inherits System.Windows.Forms.Form

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

             con.Open()

str = "select * from student;select * from customer;select * from product"

            com = New SqlCommand(str, con)

             sqlda = New SqlDataAdapter(com)

             ds = New DataSet

             sqlda.SelectCommand.CommandText = str

             sqlda.Fill(ds)

             DataGrid1.DataSource = ds

    End Sub