已经有一个打开的 DataReader。有不同的comaand使用但没有解决

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

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

Answer 2

MARS is what you are looking for. You have start new DataReader before finishing the previous one. It is not allowed by default, so you have to specify that option 创建连接时在连接字符串中：

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

已经有一个打开的 DataReader。有不同的comaand使用但没有解决

There is already an open DataReader. There is different comaand use but not resolve

c#

datareader