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：
其中T_Major是专业表，T_Student是学生表，StudentId是学号，MajorId是专业Id，T_Major与T_Student是一对多的关系。
2. 项目中添加数据库实体模型
因为之前没有配置过数据库连接，所以点击“新建库连接”，如果之前配置过数据库连接，可以直接从下拉列表中选择或者新建
选择需要生成的表/存储过程等
点击“完成”
这里会弹出如下图的窗口，然后选择确定(如果再弹出，也选择确定)，如果不小心点击了取消，可以在模型设计界面Ctrl + S(保存的快捷键)，或如下图的操作，然后会弹出窗口，一直确定就行。
这里是使用MVC，所以添加一个控制器来测试（这里为了快速生成读写的控制器方法，选择“包含读/写操作的MVC5控制器”）
生成代码如下：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
|
using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.Mvc;namespace Zhong.Web.Controllers{ public class StudentController : Controller { // GET: Student public ActionResult Index() { return View(); } // GET: Student/Details/5 public ActionResult Details(int id) { return View(); } // GET: Student/Create public ActionResult Create() { return View(); } // POST: Student/Create [HttpPost] public ActionResult Create(FormCollection collection) { try { // TODO: Add insert logic here return RedirectToAction("Index"); } catch { return View(); } } // GET: Student/Edit/5 public ActionResult Edit(int id) { return View(); } // POST: Student/Edit/5 [HttpPost] public ActionResult Edit(int id, FormCollection collection) { try { // TODO: Add update logic here return RedirectToAction("Index"); } catch { return View(); } } // GET: Student/Delete/5 public ActionResult Delete(int id) { return View(); } // POST: Student/Delete/5 [HttpPost] public ActionResult Delete(int id, FormCollection collection) { try { // TODO: Add delete logic here return RedirectToAction("Index"); } catch { return View(); } } }} |
同样的方法添加一个Major控制器
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
|
using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.Mvc;namespace Zhong.Web.Controllers{ public class MajorController : Controller { // GET: Major public ActionResult Index() { return View(); } // GET: Major/Details/5 public ActionResult Details(int id) { return View(); } // GET: Major/Create public ActionResult Create() { return View(); } // POST: Major/Create [HttpPost] public ActionResult Create(FormCollection collection) { try { // TODO: Add insert logic here return RedirectToAction("Index"); } catch { return View(); } } // GET: Major/Edit/5 public ActionResult Edit(int id) { return View(); } // POST: Major/Edit/5 [HttpPost] public ActionResult Edit(int id, FormCollection collection) { try { // TODO: Add update logic here return RedirectToAction("Index"); } catch { return View(); } } // GET: Major/Delete/5 public ActionResult Delete(int id) { return View(); } // POST: Major/Delete/5 [HttpPost] public ActionResult Delete(int id, FormCollection collection) { try { // TODO: Add delete logic here return RedirectToAction("Index"); } catch { return View(); } } }} |
由于学生表MajorId依赖于Major表，所以需要先有专业，才能新增学生数据(这里不讨论是否合理)
编写逻辑代码，创建视图
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
|
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 MajorController : Controller { // GET: Major public ActionResult Index() { var majors = new EFDbEntities().T_Major.ToList(); return View(majors); } // GET: Major/Details/5 public ActionResult Details(int id) { var major = new EFDbEntities().T_Major.Find(id); if (major == null) { return Content("参数错误"); } return View(major); } // GET: Major/Create public ActionResult Create() { return View(); } // POST: Major/Create [HttpPost] public ActionResult Create(T_Major entity) { if (entity != null) { var entities = new EFDbEntities(); entities.T_Major.Add(entity); entities.SaveChanges(); } return RedirectToAction("Index"); } // GET: Major/Edit/5 public ActionResult Edit(int id) { var entity = new EFDbEntities().T_Major.Find(id); if (entity == null) { return Content("参数错误"); } return View(entity); } // POST: Major/Edit/5 [HttpPost] public ActionResult Edit(T_Major entity) { if (entity == null) { return Content("参数错误"); } var entities = new EFDbEntities(); #region 方式一 ////该方式一般是根据主键先读取数据，然后再逐个赋值，最后更新 //var oldEntity = entities.T_Major.Find(entity.Id); //if (oldEntity!=null) //{ // oldEntity.Name = entity.Name; // entities.SaveChanges(); //} #endregion #region 方式二 //该方式是直接将新的实体(可能是new出来的并且对主键等的属性赋值好了)附加到上下文，然后标记状态为修改Modified entities.T_Major.Attach(entity); entities.Entry(entity).State = System.Data.Entity.EntityState.Modified; entities.SaveChanges(); #endregion return RedirectToAction("Index"); } // GET: Major/Delete/5 public ActionResult Delete(int id) { var major = new EFDbEntities().T_Major.Find(id); return View(major); } // POST: Major/Delete/5 [HttpPost] public ActionResult Delete(int id, FormCollection collection) { try { // TODO: Add delete logic here var entities = new EFDbEntities(); var major = entities.T_Major.Find(id); entities.T_Major.Remove(major); entities.SaveChanges(); return RedirectToAction("Index"); } catch { return View(); } } }} |
添加专业：
专业列表：
同样实现学生控制器与视图：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
|
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"); } }} |
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。
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持服务器之家。
