public ActionResult tag(string id)
        {
            id = Server.UrlDecode(id);
            if (id != null)
            {
                var t = db.Tags.Where(m => m.TagName == id);
                if(t.Count()==0||t.Count()>=2)
                {
                    return RedirectToAction("Index");
                }
                int tid = t.SingleOrDefault().TagID;
                var articles = db.Tag_relationships.Include("Articles").Where(m => m.TagID == tid).ToList();
                ViewBag.tagname = id;
                return View(articles);


            }
            else
            {
                return RedirectToAction("Index");
            }

@model IEnumerable<Blog.Models.Tag_relationship>
@foreach (var item in Model.Take(10))
{
    <li><a href="/Read/Blog/@item.ArticleID">@item.Articles.Title</a>
</li>
}

routes.MapRoute(
                "Tag",
                "tag/{id}",
                new { controller = "Tag", action = "tag", id = UrlParameter.Optional }
                );