////验证用户名是否与注册数据库中的重名！！！
Private Sub check_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles check.Click
        Dim myConnection As OleDbConnection
        Dim myCommand As OleDbCommand
        Dim dbname As String
        dbname = Server.MapPath("db1.mdb")
        myConnection = New OleDbConnection("PROVIDER=Microsoft.Jet.OLEDB.4.0;DATA Source=C:\Documents and Settings\Administrator\My Documents\Visual Studio Projects\WebApplication1 (2)\database\db1.mdb")数据库所在的目录

        If userid.Text = "" Then
            Label5.Text = "error!!you must complete it"
        Else

            Dim checklogin As String
            checklogin = "select * from users "

            Dim cmd As New OleDbCommand(checklogin, myConnection)
            Dim reader As OleDbDataReader

            Try
                myConnection.Open()
                reader = cmd.ExecuteReader()
                reader.Read()

                If userid.Text = reader("userid") Then
                    Label5.Text = "the userid had been used"
                Else
                    Label5.Text = "this userid can use"
                End If
            Catch err As Exception
                Trace.Write(err.Message)
                Label5.Text = "checked error"
            Finally
                If (Not myConnection Is Nothing) Then
                    myConnection.Close()
                End If

            End Try
        End If
    End Sub

////用户注册
 Private Sub regist_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles regist.Click
        Dim myConnection As OleDbConnection
        Dim myCommand As OleDbCommand
        Dim dbname As String
        dbname = Server.MapPath("db1.mdb")
        myConnection = New OleDbConnection("PROVIDER=Microsoft.Jet.OLEDB.4.0;DATA Source=C:\Documents and Settings\Administrator\My Documents\Visual Studio Projects\WebApplication1 (2)\database\db1.mdb")
        Dim strinsert As String
        strinsert = "insert into users("
        strinsert &= "u_id,u_password)"
        strinsert &= "values(''''"
        strinsert &= userid.Text & "'''',''''"
        strinsert &= password.Text & "'''')"
        Dim cmd As New OleDbCommand(strinsert, myConnection)
        Dim added As Integer
        Try
            myConnection.Open()
            added = cmd.ExecuteNonQuery
            If added > 0 Then
                Label5.Text = "your information is added"
                Response.Redirect("home.aspx")

            End If
        Catch err As Exception
            Trace.Write(err.Message)
            Label5.Text = "added error"
        Finally
            If (Not myConnection Is Nothing) Then
                myConnection.Close()
            End If
        End Try

    End Sub

/////

////