.net中点击button按钮显示下一条记录（上一条 下一条）

/// <summary>
    /// 取出前后新闻,产生连接,如果前后都有则占2行.
    /// </summary>
    /// <param name="articleid">目前记录id</param>
    /// <returns></returns>
    public string _4S_article_link(string articleid, string page)
    {
        StringBuilder str = new StringBuilder("");
        con.SetDefaultConnection(constr);
        string sql = "SELECT classname FROM db_article WHERE (articleid = @articleid)";
        SqlParameter[] prams = new SqlParameter[1];
        prams[0] = new SqlParameter("@articleid", articleid);
        DataRow row = con.Row(sql, prams);
        string classname = row["classname"].ToString();
        sql = "SELECT TOP 1 articleid FROM db_article WHERE (articleid < @articleid) AND (classname = '" + classname + "') ORDER BY articleid DESC";
        prams[0].ParameterName = "@articleid";
        prams[0].Value = articleid;

        row = con.Row(sql, prams);
        if (row != null)
        {
            str.Append("<a href='"+page+"?id=" + classname.Substring(5) +"&articleid=");
            str.Append(row["articleid"].ToString());
            str.Append("'><span style='color: #000099'>上一条");
            str.Append("</span></a>");
        }
        sql = "SELECT TOP 1 articleid FROM db_article WHERE (articleid > @articleid) AND (classname = '" + classname + "') ORDER BY articleid";
        row = con.Row(sql, prams);
        if (row != null)
        {
            str.Append("&nbsp;&nbsp;&nbsp;&nbsp;<a href='"+page+"?id=" + classname.Substring(5) + "&articleid=");
            str.Append(row["articleid"].ToString());
            str.Append("'><span style='color: #000099'>下一条");
            str.Append("</span></a>&nbsp;&nbsp;&nbsp;&nbsp;");
        }
        else
            str.Append("&nbsp;&nbsp;&nbsp;&nbsp;");
        return str.ToString();
    }