VB.NET中的数据库访问 [英] Database Access in VB.NET

问题描述

我使用以下代码访问了VB.NET中的数据库：

I have accessed a database in VB.NET using the following code:

Public Class Form1
    Private Sub btnLoad_Click(ByVal sender As System.Object, _
      ByVal e As System.EventArgs) Handles btnLoad.Click
        Dim con As OleDb.OleDbConnection = New OleDb.OleDbConnection
        Dim dbProvider As String
        Dim dbSource As String
        Dim ds As New DataSet
        Dim da As OleDb.OleDbDataAdapter
        Dim sql As String

        dbProvider = "PROVIDER=Microsoft.Jet.OLEDB.4.0;"
        dbSource = "Data Source = AddressBook.mdb"
        con.ConnectionString = dbProvider & dbSource
        con.Open()
        sql = "SELECT * FROM tblContacts"
        da = New OleDb.OleDbDataAdapter(sql, con)
        da.Fill(ds, "Address Book")
        MsgBox("Database Open")
        con.Close()
        MsgBox("Database Closed")
        txtFirstName.Text = ds.Tables("AddressBook").Rows(0).Item(1)
        txtSurname.Text = ds.Tables("AddressBook").Rows(0).Item(2)
    End Sub
End Class  

但是在 txtFirstName.Text = ds.Tables（ AddressBook）。Rows（0）.Item（ 1），这给了我一个例外，说应该创建对象的实例。我不明白到底是什么问题。我该如何创建实例，又该创建一个实例呢？

However in line "txtFirstName.Text = ds.Tables("AddressBook").Rows(0).Item(1)", it gives me an exception saying that an instance of an object should be created. I am not understanding what exactly the problem is. How can I create an instance, and of WHAT should I create an instance?

推荐答案

您在

da.Fill(ds, "Address Book") 

但是没有空格

txtFirstName.Text = ds.Tables("AddressBook").Rows(0).Item(1)

用于表的名称。因此，名称为 AddressBook的表不存在。

For the name of the table. Therefore a table with name "AddressBook" does not exist.

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