dropdownlist อีกแล้ว ได่ตัวอย่างมาค่ะ และมีปัญหาอยู่ว่าเวลาใช้ where มันจะรันไม่ผ่านแจ้งติดตรง

Imports System.Data
Imports System.Data.SqlClient
Imports System.Data.OleDb
Partial Class _Default
    Inherits System.Web.UI.Page

    Private conStr As String = "Provider=Microsoft.Jet.OLEDB.4.0 ;Data Source=" & Server.MapPath("thailand.mdb")
    'Private conStr As String = "Server=(local);database=reservation_system;uid=rssadmin;password=PAma22"
    ' Protected WithEvents Dropdownlist1 As System.Web.UI.WebControls.DropDownList
    ' Protected WithEvents Dropdownlist2 As System.Web.UI.WebControls.DropDownList
    ' Protected WithEvents Dropdownlist3 As System.Web.UI.WebControls.DropDownList

    Private Shared dsChild As New DataSet
  
    Dim ds1 As New DataSet()
    Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load, Me.Load
        'Put user code to initialize the page here
        If IsPostBack = False Then
            BindDropDownList()
        End If

    End Sub

    Private Sub BindDropDownList()
        Dim conn As New OleDbConnection(conStr)
        conn.Open()
        Dim ds As New DataSet()
        Dim da As New OleDbDataAdapter("Select * From geography ", conn)
        da.Fill(ds, "geography")
        droBuild.DataSource = ds.Tables("geography")
        droBuild.DataTextField = ("GEO_NAME")
        droBuild.DataValueField = ("GEO_ID")
        droBuild.DataBind()
        da.Dispose()
        conn.Dispose()
        BindDropDownListChild()
    End Sub

    Private Sub BindDropDownListChild()
        Dim conn As New OleDbConnection(conStr)
        conn.Open()
        Dim da1 As New OleDbDataAdapter("Select * From province Where GEO_ID ='" & droBuild.SelectedValue & "'", conn) '***ตรงนี้ค่ะ***
        dsChild = New DataSet
        da1.Fill(dsChild, "province")
        droFloor.Items.Clear()
        droFloor.DataSource = dsChild.Tables("province")
        droFloor.DataTextField = ("PROVINCE_NAME")
        droFloor.DataValueField = ("GEO_ID") ' binding
        droFloor.DataBind()
        da1.Dispose()
        conn.Dispose()
        'DisplayImage()
    End Sub

    'Private Sub DisplayImage()
    'Dim sSel As String = "FLOOR = " & droFloor.SelectedValue
    ' If dsChild.Tables.Count > 0 Then
    ' Dim dr() As DataRow = dsChild.Tables(0).Select(sSel)
    'Dim Path As String Path = IIf(dr.Lenght > 0, dr(0)("MAP_PATH"), String.Empty).ToString() 

    '  If dr.Length > 0 Then
    ' Dim Path As String = dr(0)("MAP_PATH") 
    ' Response.Write(Path)
    ' End If
    '  End If
    ' End Sub

    Private Sub DropDownList_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs)

        Dim ctrlId As String = CType(sender, DropDownList).ID.ToLower()
        Select Case ctrlId
            Case "droBuild"
                BindDropDownListChild()
                'droFloor.DataBind()
            Case "droFloor"

                ' DisplayImage()
            Case "db"
            Case Else

        End Select
    End Sub

End Class