未将对象引用设置到对象的实例 急!!!!!!急!!!请各位大虾求救呀
出错: DropDownList1.DataSource = objds.Tables(" DropDownList1").DefaultViewImports System.Data
Imports System.Data.oledb
Public Class WebForm1
Inherits System.Web.UI.Page
#Region " Web 窗体设计器生成的代码 "
'该调用是 Web 窗体设计器所必需的。
<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
End Sub
Protected WithEvents RadioButton12 As System.Web.UI.WebControls.RadioButton
Protected WithEvents pagemode2 As System.Web.UI.WebControls.RadioButton
Protected WithEvents Label1 As System.Web.UI.WebControls.Label
Protected WithEvents DropDownList1 As System.Web.UI.WebControls.DropDownList
Protected WithEvents Button1 As System.Web.UI.WebControls.Button
Protected WithEvents DataGrid1 As System.Web.UI.WebControls.DataGrid
'注意: 以下占位符声明是 Web 窗体设计器所必需的。
'不要删除或移动它。
Private designerPlaceholderDeclaration As System.Object
Private Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init
'CODEGEN: 此方法调用是 Web 窗体设计器所必需的
'不要使用代码编辑器修改它。
InitializeComponent()
End Sub
#End Region
Dim objconn As OleDbConnection
Dim objcmd As OleDbDataAdapter
Dim objds As DataSet
Dim strsql, strdsn As String
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
If Not Page.IsPostBack Then
strsql = "select distinct 作者 from 书籍1"
strdsn = "provider=microsoft.jet.oledb.4.0;data source=" & Server.MapPath("mydb.mdb")
objconn = New OleDbConnection(strdsn)
objcmd = New OleDbDataAdapter
objcmd.TableMappings.Add("table", " DropDownList1")
objcmd.SelectCommand = New OleDbCommand(strsql, objconn)
objds = New DataSet(" DropDownList1")
objcmd.Fill(objds)
DropDownList1.DataSource = objds.Tables(" DropDownList1").DefaultView
DropDownList1.DataBind()
End If
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim strau As String
strdsn = "provider=microsoft.jet.oledb.4.0;data source=" & Server.MapPath("mydb.mdb")
objconn = New OleDbConnection(strdsn)
strau = Trim(DropDownList1.SelectedItem.Text)
strsql = "select * from 书籍1 where 作者= '" & strau & " '"
objcmd = New OleDbDataAdapter
objcmd.TableMappings.Add("table", "book2")
objcmd.SelectCommand = New OleDbCommand(strsql, objconn)
objds = New DataSet("book2")
objcmd.Fill(objds)
DataGrid1.DataSource = objds.Tables("book2").DefaultView
DataGrid1.DataBind()
End Sub
End Class
[[it] 本帖最后由 twtdd 于 2008-6-17 16:49 编辑 [/it]]