无法连接到远程MS Access数据库 [英] Cant connect to remote MS Access database

问题描述

我不断收到一个

出现InvalidOperationException：ExecuteReader需要一个开放和可用的连接。连接的当前状态为已关闭。]

这是因为我的连接​​被关闭。有什么不对我的连接字符串？为什么不打开它。

 保护无效的Page_Load（对象发件人，EventArgs的发送）
    {
        //声明部分        // OleDbConnection的objDBConn;
        OleDbCommand的objCmd;
        OleDbDataReader objDR;        //创建连接对象
        System.Data.OleDb.OleDbConnection康恩=新
          System.Data.OleDb.OleDbConnection（）;        //修改连接字符串，并包括任何
        //其他所需的属性数据库。
        conn.ConnectionString = @供应商= Microsoft.Jet.OLEDB.4.0; +
            @数据来源= C：\\的Inetpub \\ wwwroot的\\ cm485a2 \\ rreAccesscm485a2.mdb          //使用SQL创建OleDbCommand对象执行
            objCmd =新的OleDbCommand（SELECT *+
                            客户+
                            ORDER BY CUST_ID，康恩）;            //创建一个DataReader并执行命令
            objDR = objCmd.ExecuteReader（）;            //从DataReader的复制结果DataGrid对象
            GridView1.DataSource = objDR;
            GridView1.DataBind（）;
            //关闭所有对象
            conn.Close（）;
            conn.Dispose（）;    }
 

解决方案

您需要先打开连接。

的http://msdn.microsoft.com/en-us/library/system.data.oledb.oledbconnection.open.aspx

另外，我会使用使用要避免资源泄漏，是这样的：

 使用（VAR连接=新的OleDbConnection（））
{
  connection.Open（）;
  使用（VAR命令=新的OleDbCommand（的connectionString））
  {
     //做我的东西。
  }
}
 

这方面是比较容易的GC离开未收集资源。

心连心

I keep getting a

InvalidOperationException: ExecuteReader requires an open and available Connection. The connection's current state is closed.]

It is because my connection is closed. What is wrong with my connection string? Why won't it open.

    protected void Page_Load(object sender, EventArgs e)
    {
        // Declaration section

        //OleDbConnection objDBConn;
        OleDbCommand    objCmd;
        OleDbDataReader objDR;

        //create connection object
        System.Data.OleDb.OleDbConnection conn = new
          System.Data.OleDb.OleDbConnection();

        // Modify the connection string and include any
        // additional required properties for your database.
        conn.ConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;" +
            @"Data source= c:\inetpub\wwwroot\cm485a2\rreAccesscm485a2.mdb";

          // Create OleDbCommand object with SQL to execute
            objCmd = new OleDbCommand("SELECT * " +
                            "  FROM customers " +
                            " ORDER BY cust_id", conn);

            // Create a DataReader and execute the command
            objDR = objCmd.ExecuteReader();

            // Copy results from DataReader to DataGrid object
            GridView1.DataSource = objDR;
            GridView1.DataBind();


            //close all objects
            conn.Close();
            conn.Dispose();

    }

解决方案

You need to Open the connection first.

http://msdn.microsoft.com/en-us/library/system.data.oledb.oledbconnection.open.aspx

also, I would use using to be avoid resource leaks, something like this:

using (var connection = new OleDbConnection())
{
  connection.Open();
  using (var command = new OleDbCommand("connectionString"))
  {
     //Do my stuff.
  }
}

This ways is easier to leave resources uncollected by the GC.

HTH

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