MVC对数据库增删改查，使用实体模型

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使用了MVC之后，对数据库的操作变得简单多了。创建MVC后，在model层添加一个ADO.NET实体数据模型。对应于我们要操作的数据库的表。

在控制器编写如下代码，注意一个控制器应对应于一个视图，如果一个视图对应于两个控制器，那么在行为前加上[HttpPost]，那么此行为为post时执行。默认为GET。

DbContext为上下文对象，很重要的一个要记住的类。我们新建的实体数据模型名为 Database1Entities；

public ActionResult Index()
        {
            DbContext db = new Database1Entities();//子类赋值给父类
            IQueryable<Table> t1 = db.Set<Table>();//将所有数据传入
            return View(t1);//返回到VIEW中
        }

//控制器所有代码如下

using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using crud.Models;
using System.Data.Entity.Migrations;
using System.Web.Routing;

namespace crud.Controllers
{
    public class CRUDController : Controller
    {
        //
        // GET: /CRUD/

        public ActionResult Index()
        {
            DbContext db = new Database1Entities();
            IQueryable<Table> t1 = db.Set<Table>();
            return View(t1);
        }
        public ActionResult create()
        {
            return View();
        }
        [HttpPost]
        public ActionResult create(Table t1)
        {
            DbContext db = new Database1Entities();
            db.Set<Table>().Add(t1);
            int res= db.SaveChanges();
            if (res>0)
            {
                return Redirect(@Url.Action("index","crud"));
            }
            else
            {
                return Redirect(@Url.Action("create","crud"));
            }
        }
        public ActionResult delete(int Id)
        {
            DbContext db = new Database1Entities();
            var deleteVal = db.Set<Table>().Where(u => u.Id == Id).FirstOrDefault();
            db.Set<Table>().Remove(deleteVal);
            int res=db.SaveChanges();
            if (res>0 )
            {
               return Redirect(@Url.Action("INDEX","CRUD"));
            }
            else
            {
                return Redirect(@Url.Action("", ""));
            }
        }
        public ActionResult change(int Id)
        {
            DbContext db = new Database1Entities();
            ViewData.Model=db.Set<Table>().Where(u=>u.Id==Id).FirstOrDefault();
            //IQueryable<Table> iq = db.Set<Table>().Where(u => u.Id == Id);
            return View();
        }
        [HttpPost]
        public ActionResult change(Table table)
        {
            DbContext db = new Database1Entities();
            IQueryable<Table> iq = db.Set<Table>().Where(u => u.Id == table.Id);
            db.Set<Table>().AddOrUpdate(table);
            db.SaveChanges();
            return Redirect(@Url.Action("index","CRUD"));
        }
    }
}

//VIEW代码如下

@using crud.Models
@model IQueryable< crud.Models.Table>
@{
    Layout = null;
}
<!DOCTYPE html>
<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>Index</title>
</head>
<body>
    <div>
        @Html.ActionLink("Add", "create", "CRUD");
        <br />
        <table border="1">
            <tr>
                <th>id</th>
                <th>username</th>
                <th>delete</th>
            </tr>
            @foreach (Table table in Model)
            {
                <tr>
                    <td>@table.Id</td>
                    <td>@table.username</td>
                    <td>@Html.ActionLink("delete", "delete", "CRUD", new RouteValueDictionary(new {Id=@table.Id}),null)</td>
                    <td>@Html.ActionLink("change","change","CRUD",new RouteValueDictionary(new {Id= @table.Id}),null)</td>
                </tr>
            }
        </table>
    </div>
</body>
</html>
//创建代码如下

@model crud.Models.Table
@{
    Layout = null;
}

<!DOCTYPE html>

<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>create</title>
</head>
<body>
    <div>
        @using (Html.BeginForm("create", "crud", FormMethod.Post))
        {
            <span>username</span>
            @Html.TextBoxFor(u => u.username)
            <br />
            <input type="submit" value="Click" />
        }
    </div>
</body>
</html>
//修改代码如下

@model crud.Models.Table
@{
    Layout = null;
}

<!DOCTYPE html>

<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>change</title>
</head>
<body>
    <div>
        @using (Html.BeginForm("change", "crud", FormMethod.Post))
        {
            @Model.Id
            @Html.HiddenFor(n => n.Id)
            @Html.TextBoxFor(n=>n.username)
            <input type="submit" value="change" />
          }
    </div>
</body>
</html>

完成

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