VB.NET如何在listbox中显示数据库的某一字段的内容(ACCESS)

Private Sub frmInput_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
dim sqlstring as string="select 凭证字 from 凭证字"
Dim connstr as String="Provider=Microsoft.Jet.Oledb.4.0;"& "Data source=rent.mdb"
Dim ConnTemp As New OleDb.OleDbConnection
Dim RSTemp As OleDb.OleDbDataReader
ConnTemp.ConnectionString = connstr
Dim CmdTemp As New OleDb.OleDbCommand(sqlstring, ConnTemp)
ConnTemp.Open()
RSTemp = CmdTemp.ExecuteReader
Do While RSTemp.Read
ListBox1.Items.Add(RSTemp(0))
Loop
RSTemp.Close()
conntemp.close