数据访问方式之EntityFramework（2）

private readonly DBContext _db = new DBContext();

return View(_db.Product.ToList());

var list = _db.Product.OrderByDescending(s => s.Id).Skip(rows * (page - 1)).Take(rows).ToList();
var records = _db.Product.Count();
var total = records > 0 ? (records % rows == 0 ? records / rows : records / rows + 1) : 0;
return Json(new { rows = list, total, page, records });

@model IEnumerable<WebApplication.DAL.Product>

Product product = _db.Product.Find(id);

 if (ModelState.IsValid)
        {
            _db.Product.Add(product);
            _db.SaveChanges();
            return RedirectToAction("Index");
        }

if (ModelState.IsValid)
        {
            _db.Entry(product).State = EntityState.Modified;
            _db.SaveChanges();
            return RedirectToAction("Index");
        }

        Product product = _db.Product.Find(id);
        _db.Product.Remove(product);
        _db.SaveChanges();
        return RedirectToAction("Index");