请教：：hamadou(闵峰)大哥代码中的一点问题。高手给指点下

Private ds As New DataSet()
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim cmd1 As New SqlCommand("select * from province", SqlCon)

“这里的sqlcon是什么？我用的是access库，总提示没有声明。我换过cn(cn="Provider=Microsoft.Jet.OLEDB.4.0;Data source=..\股票.mdb").可是提示 类型“String”的值无法转换为“System.Data.SqlClient.SqlConnection”。高手指点啊

Dim cmd2 As New SqlCommand("select * from city", SqlCon)
Dim cmd3 As New SqlCommand("select * from county ", SqlCon)
Dim dpr1 As New SqlDataAdapter(cmd1)
Dim dpr2 As New SqlDataAdapter(cmd2)
Dim dpr3 As New SqlDataAdapter(cmd3)
dpr1.Fill(ds, "province")
dpr2.Fill(ds, "city")
dpr3.Fill(ds, "county")
Me.ComboBox1.DataSource = ds.Tables("province")
Me.ComboBox1.DisplayMember = "pname"
Me.ComboBox1.ValueMember = "pid"
setdata()
End Sub
Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
If Not Me.ComboBox1.Focus Then Exit Sub
setdata()
End Sub
Private Sub setdata()
Dim pid As Integer = Me.ComboBox1.SelectedValue
Dim view As New DataView(ds.Tables("city"), "pid=" & CStr(pid), "pid", DataViewRowState.CurrentRows)
If view.Count < 1 Then
Me.ComboBox2.DataSource = Nothing
Me.ComboBox2.Items.Clear()
Me.ComboBox2.SelectAll()
Me.ComboBox2.Focus()
SendKeys.Send("{delete}")

Else
Me.ComboBox2.DataSource = Nothing
Me.ComboBox2.DataSource = view
Me.ComboBox2.DisplayMember = "cname"
Me.ComboBox2.ValueMember = "cid"
End If

End Sub