使用 app.config 在 vb.net 2012 中连接字符串以进行 ms 访问

Question

您好，我是 vb.net 的新手，我创建了一个表单，我需要至少调用 4 到 5 次连接。所以我写了4-5次连接字符串进行连接。但我知道我可以使用 app.config 文件来保存连接字符串。所以我尝试了下面的代码

app.config 文件

<?xml version="1.0" encoding="utf-8" ?>
   <configuration>
      <configSections>
      </configSections>
      <connectionStrings>
       <add name="ConString"    connectionString="Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\kumar\Desktop\prodb.accdb;"/>
      </connectionStrings>
     <startup>
       <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
    </startup>
      </configuration>

vb.net 形式

Imports System.Configuration


Public Class form1
    Dim con As System.Data.OleDb.OleDbConnection
    Dim cmd As System.Data.OleDb.OleDbCommand
    Dim dr As System.Data.OleDb.OleDbDataReader
    Dim sqlstr As String
 Private Sub Button4_Click_1(sender As Object, e As EventArgs) Handles Button4.Click
        Dim connectionString As String = ConfigurationManager.ConnectionStrings("ConString").ConnectionString

        Try
            con = New System.Data.OleDb.OleDbConnection("connectionString")
            con.Open()
            Dim ds As DataSet = New DataSet
            Dim adapter As New OleDb.OleDbDataAdapter
            Dim sql As String
            Dim s As String
            s = txtsearch.Text
            sql = "select icode as `Item Code` , iname as `Name` ,irate as `Rate`,icomment as `Comment` from iteminfo   "

            adapter.SelectCommand = New OleDb.OleDbCommand(sql, con)
            adapter.Fill(ds)
            DataGridView1.DataSource = ds.Tables(0)
        Catch ex As Exception
            MsgBox("error found")
        End Try


    End Sub

但无法访问数据库。

我已添加参考system.configuration。

Answer 1

在这一行中，只需将“connectionString”替换为 connectionString con = New System.Data.OleDb.OleDbConnection("connectionString")

只需删除引号即可解决您的问题...