Question

我是编程新手。我想要完成的是在VB.NET中填写9个文本框，使用组合框（CbbNaamfirma）读取访问表TblKlanten。我不能让这个为我的生活工作;我一直在寻找这个简单的东西6个小时。你们有人可以帮助我吗？我在SO.com上阅读了很多这样的线程，它们都不适合我。我现在的代码：

Private Sub CbbNaamfirma_SelectedIndexChanged(sender As System.Object, e As           System.EventArgs) Handles CbbNaamfirma.SelectedIndexChanged
Dim Connection As New OleDb.OleDbConnection
    Connection.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source='" & Application.StartupPath & "\Database.accdb.'"
    Try
        Connection.Open()
        Dim query As String
        query = "SELECT Adres FROM TblKlanten WHERE [Naam firma] = ' " & CbbNaamfirma.Text & " ' "
        Dim cmd As New OleDbCommand(query, Connection)
        Dim Reader As OleDbDataReader = cmd.ExecuteReader
        Reader = cmd.ExecuteReader
        While Reader.Read
           TxtAdresprev.Text = Reader.GetString("Adres")
        End While
        Connection.Close()
    Catch ex As OleDbException
        MessageBox.Show(ex.Message)
    Finally
        Connection.Dispose()
    End Try
End Sub

提前谢谢你。希望代码块好转吗？

Answer 1

要改变的第一件事是使用参数化查询从数据库中读取。请注意，您的代码无法找到任何内容，因为您在组合框的值之前和之后添加了空格。

然后你需要开始在一次性物体周围使用using语句，以确保正确关闭和处理

最后，OleDbDataReader的GetString方法想要在返回的字段列表中有一个数字索引，而不是字段的名称

Private Sub CbbNaamfirma_SelectedIndexChanged(sender As System.Object, e As System.EventArgs) Handles CbbNaamfirma.SelectedIndexChanged
    Dim cnString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" & _
                    Application.StartupPath & "\Database.accdb"
    Dim query = "SELECT Adres FROM TblKlanten WHERE [Naam firma] = ?"
    Using Connection = New OleDb.OleDbConnection(cnString)
    Using cmd = New OleDbCommand(query, Connection)
        Try
           Connection.Open()
           cmd.Parameters.AddWithValue("@p1", CbbNaamfirma.Text) 
           Using Reader = cmd.ExecuteReader
               While Reader.Read
                  Dim posAdres = Reader.GetOrdinal("Adres")
                  TxtAdresprev.Text = Reader.GetString(posAdres)
                  .... other text boxes for other fields here.....
              End While
           End Using

       Catch ex As OleDbException
           MessageBox.Show(ex.Message)
       End Try
   End Using
   End Using
End Sub

您的连接字符串似乎也是错误的。在fielname错误之后不需要引用和错误

使用ComboBox VB.NET将OleDb记录读入TextBox

1 个答案: