返回值问题

Question

 public string DrawQuestionTable()
    {
        if (Request.QueryString["key"] != null)
        {
            Response.Write(Request.QueryString["key"].ToString());
            SqlConnection myconn = new SqlConnection(conn);
            myconn.Open();
            SqlCommand mycmd = new SqlCommand("select questiontitle,qcontent,qauthor,qtime,answerid from question where questionid='" + int.Parse(Request.QueryString["key"].ToString()) + "'", myconn);
            SqlDataReader DataReadQuestion = mycmd.ExecuteReader();
            string output = "<table width='100%' border='0' cellpadding='0' cellspacing='1' bordercolor='#CCCCCC'>";
            while (DataReadQuestion.Read())
            {
                output += "<tr><td></td><td>内容</td></tr>";
                output += "<tr><td rowspan=2>" + DataReadQuestion["qauthor"].ToString() + "</td><td>" + DataReadQuestion["qtime"].ToString() + "</td></tr>";
                output += "<tr><td>" + DataReadQuestion["qcontent"].ToString() + "</td></tr>";
                if (DataReadQuestion["answerid"].ToString() != null)
                {
                    SqlConnection myconn1 = new SqlConnection(conn);
                    myconn1.Open();
                    SqlCommand Answercmd = new SqlCommand("select * from answer where answerid='" + int.Parse(DataReadQuestion["answerid"].ToString()) + "'", myconn1);
                    SqlDataReader DataReadAnswerList = Answercmd.ExecuteReader();
                    while (DataReadAnswerList.Read())
                    {
                        output += "<tr><td rowspan=2>" + DataReadAnswerList["answerauthorid"].ToString() + "</td><td>" + DataReadAnswerList["answertime"].ToString() + "</td></tr>";
                        output += "<tr><td>" + DataReadAnswerList["answercontent"].ToString() + "</td></tr>";
                    }
                }
            }
            output += "</table>";
            DrawQList.Text = output;
            return output;
        }
        else
        {
            Response.Redirect("zx-index.aspx");
        }
我用这中方法在Lable里面画表,以前都能成功,现在去总是提示:   DrawQuestionTable()并非所有代码路径都有返回值这是为什么啊??

Answer 1

     return output; 
        } 
        else 
        { 
            Response.Redirect("zx-index.aspx"); 
        } 
－－－－－－－－－－－－－－－－－－else这个分支下面没有Return语句才报的这个错。

Answer 2

你可以在方法的最后或是在else分支后面加一个return null;