用VB.NET查詢一個access資料庫，代碼如下
從textbox1輸入查詢的值 按button1后查詢，將結果從label2輸出
Imports System.Data.OleDb
Public Class Form1
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
'定義一個baiOLEDB連接并實體化它
Dim con As New OleDbConnection
'定義一個OLEDB命令并實體化他
Dim cmd As New OleDbCommand
'定義一個OLEDBReader方法來讀取資料庫
Dim dr As OleDbDataReader
'初始化con的連接屬性，使用OLEDB模式，資料源為：
con.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=E:\字典專案\資料庫\dic.mdb"
'打開OLEDB資料連接
con.Open()
'初始化OLEDB命令的連接屬性為con
cmd.Connection = con
'初始化OLEDB命令的陳述句
cmd.CommandText = "select keyss from dic where ID=" & TextBox1.Text & ""
dr = cmd.ExecuteReader()
If dr.Read() Then
Label2.Text = dr(0)
End If
dr.Close()
con.Close()
End sub
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
End Sub
End Class
運行查詢的時候報錯 “dr = cmd.ExecuteReader() 至少一個引數沒有被指定值”
為什么啊
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標籤：VB.NET