How to multiple tables in Dataset - Sql Server

Imports System.Data.SqlClient
Public Class Form1
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim connetionString As String
        Dim connection As SqlConnection
        Dim command As SqlCommand
        Dim adapter As New SqlDataAdapter
        Dim ds As New DataSet
        Dim i As Integer
        Dim firstSql As String
        Dim secondSql As String

		connetionString = "Data Source=ServerName;Initial Catalog=DatabaseName;User ID=UserName;Password=Password"
		firstSql = "Your First SQL Statement Here"
		secondSql = "Your Second SQL Statement Here"
        connection = New SqlConnection(connetionString)

        Try
            connection.Open()

            command = New SqlCommand(firstSql, connection)
            adapter.SelectCommand = command
            adapter.Fill(ds, "First Table")

            adapter.SelectCommand.CommandText = secondSql
            adapter.Fill(ds, "Second Table")

            adapter.Dispose()
            command.Dispose()
            connection.Close()

            'retrieve first table data
            For i = 0 To ds.Tables(0).Rows.Count - 1
                MsgBox(ds.Tables(0).Rows(i).Item(0) & "  --  " & ds.Tables(0).Rows(i).Item(1))
            Next
            'retrieve second table data
            For i = 0 To ds.Tables(1).Rows.Count - 1
                MsgBox(ds.Tables(1).Rows(i).Item(0) & "  --  " & ds.Tables(1).Rows(i).Item(1))
            Next

        Catch ex As Exception
            MsgBox("Can not open connection ! ")
        End Try
    End Sub
End Class