Entity Framework之DB First方式

EF(Entity Framework的简称，下同)有三种方式，分别是：DataBase First、 Model First和Code First。

下面是Db First的方式：

1. 数据库库中存在两个表，一个是专业表，一个学生表，一个学生只能属于一个专业：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using Zhong.Web.Models;

namespace Zhong.Web.Controllers
{
public class StudentController : Controller
{
private EFDbEntities entities = new EFDbEntities();
// GET: Student
public ActionResult Index()
{
var students = entities.T_Student.ToList();
return View(students);
}

// GET: Student/Details/5
public ActionResult Details(int id)
{
var student = entities.T_Student.Find(id);
return View(student);
}

// GET: Student/Create
public ActionResult Create()
{
ViewData["MajorId"] = entities.T_Major.Select(m => new SelectListItem { Text = m.Name, Value = m.Id.ToString() });
return View();
}

// POST: Student/Create
[HttpPost]
public ActionResult Create(T_Student entity)
{
entities.T_Student.Add(entity);
entities.SaveChanges();
return RedirectToAction("Index");
}

// GET: Student/Edit/5
public ActionResult Edit(int id)
{
var student = entities.T_Student.Find(id);
ViewData["MajorId"] = entities.T_Major.Select(m => new SelectListItem { Text = m.Name, Value = m.Id.ToString() });
return View(student);
}

// POST: Student/Edit/5
[HttpPost]
public ActionResult Edit(T_Student entity)
{
if (entity == null)
{
return Content("参数错误");
}
entities.T_Student.Attach(entity);
entities.Entry(entity).State = System.Data.Entity.EntityState.Modified;
entities.SaveChanges();
return RedirectToAction("Index");
}

// GET: Student/Delete/5
public ActionResult Delete(int id)
{
var student = entities.T_Student.Find(id);
return View(student);
}

// POST: Student/Delete/5
[HttpPost]
public ActionResult Delete(int id, FormCollection collection)
{
var student = entities.T_Student.Find(id);
entities.T_Student.Remove(student);
entities.SaveChanges();
return RedirectToAction("Index");
}
}
}

View Code
添加学生时，报错如下：



于是在控制器中增加如下代码：



刷新页面：



编辑：



删除：



列表：



在MajorController中有介绍EF的两种更新方式