已经有一个开放的DataReader。使用了不同的命令但没有解决

Question

public void createGenericControl()
{
    string selectSQL = @"SELECT id,[empId],[eventId],[eventname]
    FROM [getTask] where empid=111 ";
    SqlCommand cmd = new SqlCommand(selectSQL, con);
    SqlDataAdapter adapter = new SqlDataAdapter(cmd);
    con.Open();

    SqlDataReader rdr = cmd.ExecuteReader();

    while (rdr.Read())
    {

      HtmlGenericControl tabs = new HtmlGenericControl("div");

      tabs.Attributes.Add("class", "panel panel-default");
      HtmlGenericControl panel = new HtmlGenericControl("div");
      panel.Attributes.Add("class", "panel-heading");


      HtmlGenericControl headAnchor = new HtmlGenericControl("a");
      headAnchor.InnerText = rdr["eventName"].ToString();
      headAnchor.Attributes.Add("class", "panel-title");
      headAnchor.Attributes.Add("data-toggle", "collapse");
      headAnchor.Attributes.Add("data-parent", "panel-530164");
      headAnchor.Attributes.Add("href", "#panel-element-" + rdr["id"].ToString());

      panel.Controls.Add(headAnchor);
      tabs.Controls.Add(panel);

      HtmlGenericControl panelElement = new HtmlGenericControl("div");

      panelElement.Attributes.Add("class", "panel-collapse collapse in");
      panelElement.Attributes.Add("id", "panel-element-" + rdr["id"].ToString());
      HtmlGenericControl panelbody = new HtmlGenericControl("div");

      panelbody.Attributes.Add("class", "panel-body");
      HtmlGenericControl row = new HtmlGenericControl("div");

      row.Attributes.Add("class", "row");
      HtmlGenericControl col = new HtmlGenericControl("div");

      col.Attributes.Add("class", "col-md-15");


      HtmlGenericControl ul = new HtmlGenericControl("ul");

      HtmlGenericControl li = new HtmlGenericControl("li");
      string selectSQL1 = @"select myevents.eventName,eventDescription from  myevents inner join
    dbo.getTask on myevents.eventName=gettask.eventName ";
      SqlCommand locationCommand = new SqlCommand(selectSQL1, con);
      SqlDataAdapter adapter1 = new SqlDataAdapter(locationCommand);
      SqlDataReader rdr1 = locationCommand.ExecuteReader();
      while (rdr1.Read())
      {
          li = new HtmlGenericControl("li");



          li.InnerText = rdr1[1].ToString();
          ul.Controls.Add(li);
          col.Controls.Add(ul);

          row.Controls.Add(col);

          panelbody.Controls.Add(row);
          panelElement.Controls.Add(panelbody);
          panelElement.Controls.Add(panelbody);
          panelElement.Controls.Add(panelbody);
          tabs.Controls.Add(panelElement);
          ulTabs.Controls.Add(tabs);
          StringWriter sw = new StringWriter();
          HtmlTextWriter w = new HtmlTextWriter(sw);
          ulTabs.RenderControl(w);
          string s = sw.GetStringBuilder().ToString();

      }
      con.Close();
    }
}

Answer 1

MARS正是您要找的。在完成上一个DataReader之前，您已经启动了新的DataReader。默认情况下不允许这样做，因此在创建连接时必须在连接字符串中使用specify that option：

string connectionString = "Data Source=MSSQL1;" +   
"Initial Catalog=AdventureWorks;Integrated Security=SSPI;" +  
"MultipleActiveResultSets=True";

Answer 2

将MultipleActiveResultSets=true;添加到您的连接字符串。