三层架构下构建数据库访问网站

1 数据访问层的编写

using SE17D.Demo3.MVC.Model;
using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace SE17D.Demo3.MVC.DAL
{
    public class StudentDal
    {
        DbContext dbContext = new BIOContext();
        //查询所有记录
        public List<STUDENT> GetList()
        {
            return dbContext.Set<STUDENT>().ToList();
        }

        //查询单个记录
        public STUDENT GetByID(int id)
        {
            return dbContext.Set<STUDENT>().Where(u => u.ID == id).FirstOrDefault();
        }

        //查询记录的条数
        public int GetCount()
        {
            return dbContext.Set<STUDENT>().Count();
        }

        //添加记录
        public int Add(STUDENT student)
        {
            dbContext.Set<STUDENT>().Add(student);
            return dbContext.SaveChanges();
        }

        //修改记录
        public int Update(STUDENT student)
        {
            dbContext.Set<STUDENT>().Attach(student);
            dbContext.Entry(student).State = EntityState.Modified;
            return dbContext.SaveChanges();
        }

        //删除记录
        public int DeleteByID(int id)
        {
            STUDENT student = dbContext.Set<STUDENT>().Where(u => u.ID == id).FirstOrDefault();
            dbContext.Entry(student).State = EntityState.Deleted;
            return dbContext.SaveChanges();
        }
    }
}

2 业务逻辑层的编写

using SE17D.Demo3.MVC.DAL;
using SE17D.Demo3.MVC.Model;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace SE17D.Demo3.MVC.BLL
{
    public class StudentBll
    {
        StudentDal studentDal = new StudentDal();
        public List<STUDENT> GetList()
        {
            return studentDal.GetList();
        }

        public STUDENT GetByID(int id)
        {
            return studentDal.GetByID(id);
        }

        public int GetCount()
        {
            return studentDal.GetCount();
        }

        public bool Add(STUDENT person)
        {
            return studentDal.Add(person) > 0;
        }

        public bool Update(STUDENT person)
        {
            return studentDal.Update(person) > 0;
        }

        public bool DeleteByID(int id)
        {
            return studentDal.DeleteByID(id) > 0;
        }
    }
}

3 用户层的控制器书写

using SE17D.Demo3.MVC.BLL;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;

namespace SE17D.Demo3.MVC.UI.Controllers
{
    public class StudentController : Controller
    {
        StudentBll studentBll = new StudentBll();
        // GET: Student
        public ActionResult Index()
        {
            return View(studentBll.GetList());
        }
        //public ActionResult Add()
        //{
        //    return View();
        //}
    }
}

运行结果

捕获.PNG