EF(Entity Framework的簡稱，下同)有三種方式，分別是：DataBase First、 Model First和Code First。
下面是Db First的方式：
1. 數據庫庫中存在兩個表，一個是專業表，一個學生表，一個學生只能屬于一個專業：
其中T_Major是專業表，T_Student是學生表，StudentId是學號，MajorId是專業Id，T_Major與T_Student是一對多的關系。
2. 項目中添加數據庫實體模型
因為之前沒有配置過數據庫連接，所以點擊“新建庫連接”，如果之前配置過數據庫連接，可以直接從下拉列表中選擇或者新建
選擇需要生成的表/存儲過程等
點擊“完成”
這里會彈出如下圖的窗口，然后選擇確定(如果再彈出，也選擇確定)，如果不小心點擊了取消，可以在模型設計界面Ctrl + S(保存的快捷鍵)，或如下圖的操作，然后會彈出窗口，一直確定就行。
這里是使用MVC，所以添加一個控制器來測試（這里為了快速生成讀寫的控制器方法，選擇“包含讀/寫操作的MVC5控制器”）
生成代碼如下：
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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(); } } }} |
同樣的方法添加一個Major控制器
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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(); } } }} |
由于學生表MajorId依賴于Major表，所以需要先有專業，才能新增學生數據(這里不討論是否合理)
編寫邏輯代碼，創建視圖
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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("參數錯誤"); } 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("參數錯誤"); } return View(entity); } // POST: Major/Edit/5 [HttpPost] public ActionResult Edit(T_Major entity) { if (entity == null) { return Content("參數錯誤"); } var entities = new EFDbEntities(); #region 方式一 ////該方式一般是根據主鍵先讀取數據，然后再逐個賦值，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 //該方式是直接將新的實體(可能是new出來的并且對主鍵等的屬性賦值好了)附加到上下文，然后標記狀態為修改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(); } } }} |
添加專業：
專業列表：
同樣實現學生控制器與視圖：
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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("參數錯誤"); } 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"); } }} |
添加學生時，報錯如下：
于是在控制器中增加如下代碼：
刷新頁面：
編輯：
刪除：
列表：
在MajorController中有介紹EF的兩種更新方式。
以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持服務器之家。
