StringBuilder sb = new StringBuilder();
        string sql = "select * from users";
        DataTable dt = DbHelperSQL.Query(sql).Tables[0];
        sb.Append("{data:[");
        for (int i = 0; i < dt.Rows.Count; i++)
        {
            sb.Append("{\"id\":\"" + dt.Rows[i]["id"].ToString() + "\",\"name\":\"" + dt.Rows[i]["name"].ToString() + "\",\"tel\":\"" + dt.Rows[i]["tel"].ToString() + "\",\"mail\":\"" + dt.Rows[i]["mail"].ToString() + "\",\"qq\":\"" + dt.Rows[i]["qq"].ToString() + "\",\"datetime\":\"" + dt.Rows[i]["addtime"].ToString() + "\"}");
            if (i != dt.Rows.Count - 1)
            {
                sb.Append(",");
            }
        }
        sb.Append("]}");
        Response.Write(sb.ToString());