Various removal methods for EF

2.1 Check if ID exists            //2.2 perform delete            models.student stu = new Models.student () {id = id};            Db. Students.attach (Stu);            Db. Students.remove (Stu);            Dbentityentry<models.student> entry = db. Entry<models.student> (Stu);            Entry. state = System.Data.EntityState.Deleted;            int res = db. SaveChanges ();            if (res>0)//delete succeeded            Response.Write ("<script>alert (' Delete succeeded ~~! '); window.location= '/stu/index ';</script> ");

  3.1.3.2 queries the class data and turns it into a drop-down box option set            list<selectlistitem> listclass = db. Classes.where (C=>c.cisdel==false). ToList ()//Query the data first and turn it into the Entity list collection                . Select (c=> new SelectListItem () {Text = c.cname, Value = C.cid. ToString (),                    Selected = (stu. CId = = c.cid)}). ToList ();//Convert entity collection to SelectListItem collection

　　

　　

Various removal methods for EF