关于sqlDataReader 阅读器嵌套的问题

放个冯老师的代码来提醒自己.

public partial class me2 : System.Web.UI.Page
{
    DB dbManager = new DB();
    int flag = 0;
    protected void Page_Load(object sender, EventArgs e)
    {
        SqlDataReader sdr = null;
        sdr = dbManager.getSdr("select id,voteTitle from votemaster");
        while (sdr.Read())
        {
            flag+=1;
            Response.Write("投票标题:"+sdr.GetString(1)+"<p>");
            int id = sdr.GetInt32(0);
           
           if (!sdr.IsClosed)
            {
                sdr.Close();
            }
            SqlDataReader sdr2 = dbManager.getSdr("select voteItem from voteDetails where id="+id);
            int first=0;
            while (sdr2.Read())
            {
                first += 1;
                Response.Write("&nbsp;&nbsp;&nbsp;&nbsp;" + first + ":" + sdr2.GetString(0)+"<br>");
            }
            if (!sdr2.IsClosed)
            {
                sdr2.Close();
            }
            if (sdr.IsClosed)
            {
                sdr = dbManager.getSdr("select id,voteTitle from votemaster");
                for (int inNum = 0; inNum < flag; inNum++)
                {
                    sdr.Read();
                }
            }
            


        }
    }
}