Entity Framework 初級學習（七）：基本 CRUD 與交易操作

本篇以程式碼示範 EF 基本新增、更新、刪除與交易處理。相關概念前六篇已涵蓋，此處專注實作。

新增實體的兩種方式

方法一：AddTo<EntitySet>(entity)

using (var edm = new NorthwindEntities()) {
  Customers c = new Customers {
    CustomerID = "c#", City = "成都市", Address = "中國四川省",
    CompanyName = "cnblogs", Country = "中國", Fax = "10086",
    Phone = "1008611", PostalCode = "610000", Region = "天府廣場",
    ContactName = "風車車.Net"
  };
  edm.AddToCustomers(c);
  int result = edm.SaveChanges();
  Assert.AreEqual(result, 1);
  Customers addc = edm.Customers.FirstOrDefault(cc => cc.CustomerID == "c#");
  Console.WriteLine("CustomerId={0}, City={1}", addc.CustomerID, addc.City);
}

方法二：AddObject(entitySetName, entity)

using (var edm = new NorthwindEntities()) {
  Customers c = new Customers { CustomerID = "c2", City = "成都市2", ... };
  edm.AddObject("Customers", c);
  int result = edm.SaveChanges();
  Assert.AreEqual(result, 1);
  // 驗證...
}

更新與刪除

更新：取得實體 → 修改屬性 → SaveChanges()。刪除：edm.DeleteObject(entity) → SaveChanges()。交易預設由 SaveChanges() 內部管理，若需跨多個 Context 或自訂隔離等級，可使用 TransactionScope。