mvc+linq+EF对数据表的查删改

         /// <summary>
        /// 查询数据库中学生姓名
        /// </summary>
        /// <returns></returns>
        public ActionResult Index()
        {
            //使用linq,查询数据上下文中的学生姓名
            List<Models.T_student> list = (from d in db.T_student select d).ToList();

            //将集合数据传给视图
            ViewData["DataList"] = list;
            return View();
        }

         <span style="white-space:pre">	</span>/// <summary>
        /// 根据学生ID删除学生
        /// </summary>
        /// <param name="id">学生ID</param>
        /// <returns></returns>
        public ActionResult Del(string id)
        {
            //创建要删除的实体，并将ID赋值给实体对象
            T_student modelDel = new T_student() { studentId = id };

            //将实体对象添加到EF管理容器
            db.T_student.Attach(modelDel);

            //将实体对象包装类标示为删除状态
            db.T_student.Remove(modelDel);

            //更新数据库
            db.SaveChanges();

            //更新成功，跳转到Index
            return RedirectToAction("Index","MyClass");}

#region 显示要修改的数据
    [HttpGet]
        /// <summary>
        /// 显示要修改的数据
        /// </summary>
        /// <param name="id">要修改的学生ID</param>
        /// <returns></returns>
        public ActionResult Modify(string id)
        {
            //根据学生ID，查询数据库，返回集合中拿到第一个实体对象
            T_student ts = (from a in db.T_student where a.studentId == id select a).FirstOrDefault();

            //查询课程名称
            IEnumerable<SelectListItem> listItem=(from c in db.T_class select c).ToList().Select(c=>new SelectListItem{Value=c.classId.ToString(),Text=c.className});
            
            //查询到的课程名称给Viewbag
            ViewBag.classList = listItem;

            //使用View，将数据传给视图上名为model的属性
            return View(ts);
        } 
        #endregion


        #region 保存要修改的数据
        [HttpPost]
        /// <summary>
        /// 保存要修改的数据
        /// </summary>
        /// <param name="id">要修改的学生ID</param>
        /// <returns></returns>
        public ActionResult Modify(T_student ts)
        {
            //将实体对象加入EF对象容器中，并获取包装类对象
            DbEntityEntry<T_student> entry=db.Entry<T_student>(ts);

            //将包装类设置为unchange
            entry.State = System.Data.EntityState.Unchanged;

            //设置被改变的属性
            entry.Property(a=>a.studentName).IsModified=true;
            entry.Property(a => a.classId).IsModified = true;

            //提交更新到数据库
            db.SaveChanges();

            //更新成功，跳转到Index
            return RedirectToAction("Index", "MyClass");
        }
        #endregion

　　 3.添加查询列表视图（Index.cshtml）

@using MyMvcTest.Models
@{
    Layout = null;
}

<!DOCTYPE html>

<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>Index</title>
    <style type="text/css">
        #tblist {
            border:1px solid #0094ff;
            600px;
            margin:10px auto;
            border-collapse:collapse;
        }
            #tblist th, td {
                border:1px solid #0094ff;
                padding:10px;
            }
    </style>
</head>
<body>
    <table id="tblist">
        <tr>
            <th>id</th>
            <th>姓名</th>
            <th>课程ID</th>
            <th>编辑</th>
        </tr>
        <!--变量action方法 设置viewData的集合数据生成html-->
        @foreach (T_student student in ViewData["DataList"] as List<T_student>)
        {
        <tr>
            <td>@student.studentId</td>
            <td>@student.studentName</td>
            <td>@student.classId</td>
            <td>
                <a href="/MyClass/del/@student.studentId">删除</a>
                <a href="/MyClass/modify/@student.studentId">修改</a>
            </td>
        </tr>
        }
    </table>

</body>
</html>

　　添加“修改”视图(modify.cshtml)

@model MyMvcTest.Models.T_student
@{
    Layout = null;
}

<!DOCTYPE html>

<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>Modify</title>
    <style type="text/css">
        #tblist {
            border: 1px solid #0094ff;
             600px;
            margin: 10px auto;
            border-collapse: collapse;
        }

            #tblist th, td {
                border: 1px solid #0094ff;
                padding: 10px;
            }
    </style>
</head>
<body>
    @using (Html.BeginForm("Modify", "MyClass", FormMethod.Post))
{
    <table id="tblist">
        <tr>
            <td colspan="2">修改：@Html.HiddenFor(a=>a.studentId)</td>
        </tr>
        <tr>
            <td>课程名称</td>
            <!--使用HtmlHepler，直接从model获取数据赋值给下拉框-->
            <td>@Html.DropDownListFor(a => a.classId, ViewBag.classList as IEnumerable<SelectListItem>)</td>
        </tr>
        <tr>
            <td>学生姓名</td>
            <!--使用HtmlHepler，直接从model获取数据赋值给文本框-->
            <td>@Html.TextBoxFor(a => a.studentName)</td>
        </tr>
        <tr>
            <td colspan="2"><input type="submit" value="确定修改">@Html.ActionLink("返回", "Index", "MyClass")</td>
        </tr>
    </table>
}
</body>
</html>