C# &引用；已经有一个打开的DataReader与此命令关联，必须先关闭该命令"；

我在这里的代码返回错误“已经有一个与此命令关联的打开的DataReader，必须先关闭它。”并且我已经在我的web.config上添加了代码“MultipleActiveResultSets=true”

        ReportViewer1.Visible = true;
        ReportViewer1.ProcessingMode = ProcessingMode.Local;

        var sqlConnection = new SQLConnectionStrings();
        var conReport = new SqlConnection(sqlConnection.strConn);
        var cmdReport = new SqlCommand();
        var myDataAdapter = new SqlDataAdapter();
        myDataAdapter.SelectCommand = cmdReport;

        SqlDataReader drReport;

        DataSet dsReport = new DataSet();
        //PerfLogDataSet();


        cmdReport.CommandType = CommandType.Text;
        cmdReport.Connection = conReport;
        conReport.Open();
        cmdReport.CommandText = baseQuery;
        drReport = cmdReport.ExecuteReader();
        myDataAdapter.Fill(dsReport); //where the error occurs
        dsReport.Tables[0].Load(drReport);
        drReport.Close();
        conReport.Close();

---

您正试图用相同的

SqlCommand

同时使用

SqlDataAdapter

和

SqlDataReader

        ReportViewer1.Visible = true;
        ReportViewer1.ProcessingMode = ProcessingMode.Local;

        var sqlConnection = new SQLConnectionStrings();
        var conReport = new SqlConnection(sqlConnection.strConn);
        var cmdReport = new SqlCommand();
        var myDataAdapter = new SqlDataAdapter();
        myDataAdapter.SelectCommand = cmdReport;

        SqlDataReader drReport;

        DataSet dsReport = new DataSet();
        //PerfLogDataSet();


        cmdReport.CommandType = CommandType.Text;
        cmdReport.Connection = conReport;
        conReport.Open();
        cmdReport.CommandText = baseQuery;
        drReport = cmdReport.ExecuteReader();
        myDataAdapter.Fill(dsReport); //where the error occurs
        dsReport.Tables[0].Load(drReport);
        drReport.Close();
        conReport.Close();

SqlDataAdapter

将结果集加载到

DataSet

或

DataTable

中

SqlDataReader

用于在结果集上一次循环一条记录，记录集样式。它们是两种不同的方法，用于访问具有两种不同意图的数据，两者都使用是没有意义的

        ReportViewer1.Visible = true;
        ReportViewer1.ProcessingMode = ProcessingMode.Local;

        var sqlConnection = new SQLConnectionStrings();
        var conReport = new SqlConnection(sqlConnection.strConn);
        var cmdReport = new SqlCommand();
        var myDataAdapter = new SqlDataAdapter();
        myDataAdapter.SelectCommand = cmdReport;

        SqlDataReader drReport;

        DataSet dsReport = new DataSet();
        //PerfLogDataSet();


        cmdReport.CommandType = CommandType.Text;
        cmdReport.Connection = conReport;
        conReport.Open();
        cmdReport.CommandText = baseQuery;
        drReport = cmdReport.ExecuteReader();
        myDataAdapter.Fill(dsReport); //where the error occurs
        dsReport.Tables[0].Load(drReport);
        drReport.Close();
        conReport.Close();

如果您试图加载

dsReport

，请删除

        ReportViewer1.Visible = true;
        ReportViewer1.ProcessingMode = ProcessingMode.Local;

        var sqlConnection = new SQLConnectionStrings();
        var conReport = new SqlConnection(sqlConnection.strConn);
        var cmdReport = new SqlCommand();
        var myDataAdapter = new SqlDataAdapter();
        myDataAdapter.SelectCommand = cmdReport;

        SqlDataReader drReport;

        DataSet dsReport = new DataSet();
        //PerfLogDataSet();


        cmdReport.CommandType = CommandType.Text;
        cmdReport.Connection = conReport;
        conReport.Open();
        cmdReport.CommandText = baseQuery;
        drReport = cmdReport.ExecuteReader();
        myDataAdapter.Fill(dsReport); //where the error occurs
        dsReport.Tables[0].Load(drReport);
        drReport.Close();
        conReport.Close();

SqlDataReader drReport;
drReport = cmdReport.ExecuteReader();
dsReport.Tables[0].Load(drReport);
drReport.Close();

因为您已经使用适配器加载了它

        ReportViewer1.Visible = true;
        ReportViewer1.ProcessingMode = ProcessingMode.Local;

        var sqlConnection = new SQLConnectionStrings();
        var conReport = new SqlConnection(sqlConnection.strConn);
        var cmdReport = new SqlCommand();
        var myDataAdapter = new SqlDataAdapter();
        myDataAdapter.SelectCommand = cmdReport;

        SqlDataReader drReport;

        DataSet dsReport = new DataSet();
        //PerfLogDataSet();


        cmdReport.CommandType = CommandType.Text;
        cmdReport.Connection = conReport;
        conReport.Open();
        cmdReport.CommandText = baseQuery;
        drReport = cmdReport.ExecuteReader();
        myDataAdapter.Fill(dsReport); //where the error occurs
        dsReport.Tables[0].Load(drReport);
        drReport.Close();
        conReport.Close();

myDataAdapter.Fill(dsReport);

---

如果要填充数据集，请尝试此代码

        ReportViewer1.Visible = true;
        ReportViewer1.ProcessingMode = ProcessingMode.Local;

        var sqlConnection = new SQLConnectionStrings();
        var conReport = new SqlConnection(sqlConnection.strConn);
        var cmdReport = new SqlCommand();
        var myDataAdapter = new SqlDataAdapter();
        myDataAdapter.SelectCommand = cmdReport;

        SqlDataReader drReport;

        DataSet dsReport = new DataSet();
        //PerfLogDataSet();


        cmdReport.CommandType = CommandType.Text;
        cmdReport.Connection = conReport;
        conReport.Open();
        cmdReport.CommandText = baseQuery;
        drReport = cmdReport.ExecuteReader();
        myDataAdapter.Fill(dsReport); //where the error occurs
        dsReport.Tables[0].Load(drReport);
        drReport.Close();
        conReport.Close();

    ReportViewer1.Visible = true;
    ReportViewer1.ProcessingMode = ProcessingMode.Local;

    var sqlConnection = new SQLConnectionStrings();
    var conReport = new SqlConnection(sqlConnection.strConn);
    var cmdReport = new SqlCommand(baseQuery);
    var myDataAdapter = new SqlDataAdapter(cmdReport,sqlConnection );

    DataSet dsReport = new DataSet();

    conReport.Open();
    myDataAdapter.Fill(dsReport);
    conReport.Close();

---

但如果你还想要什么，请描述它，更多；）

此行的目的是什么

dsReport.Tables[0]。加载（drReport）您已经用填充加载了该表。以前的执行者也是这样。
        ReportViewer1.Visible = true;
        ReportViewer1.ProcessingMode = ProcessingMode.Local;

        var sqlConnection = new SQLConnectionStrings();
        var conReport = new SqlConnection(sqlConnection.strConn);
        var cmdReport = new SqlCommand();
        var myDataAdapter = new SqlDataAdapter();
        myDataAdapter.SelectCommand = cmdReport;

        SqlDataReader drReport;

        DataSet dsReport = new DataSet();
        //PerfLogDataSet();


        cmdReport.CommandType = CommandType.Text;
        cmdReport.Connection = conReport;
        conReport.Open();
        cmdReport.CommandText = baseQuery;
        drReport = cmdReport.ExecuteReader();
        myDataAdapter.Fill(dsReport); //where the error occurs
        dsReport.Tables[0].Load(drReport);
        drReport.Close();
        conReport.Close();