private static void Update(EF_CRUD_Entities ef_crud_entities)
{
Customer larry = ef_crud_entities.Customer.FirstOrDefault(c => c.CustName.Equals("LarrySU"));
if (larry != null)
{
larry.CustName = "LarrySu";
ef_crud_entities.SaveChanges();
}
}
private static void Delete(EF_CRUD_Entities ef_crud_entities)
{
Customer larry = ef_crud_entities.Customer.FirstOrDefault(c => c.CustName.Equals("LarrySu"));
if (larry != null)
{
// already set Cascade
ef_crud_entities.Customer.Remove(larry);
ef_crud_entities.SaveChanges();
}
}
public static void Main(string[] args)
{
Console.WriteLine("請選擇CRUD功能:");
Console.WriteLine("C => Create");
Console.WriteLine("LR => Lazy_Read");
Console.WriteLine("ER => Eager_Read");
Console.WriteLine("U => Update");
Console.WriteLine("D => Delete");
string function = Console.ReadLine();
if (!string.IsNullOrEmpty(function))
{
try
{
EF_CRUD_Entities ef_crud_entities = new EF_CRUD_Entities();
ef_crud_entities.Database.Log = Console.Write;
switch (function)
{
case "C":
Create(ef_crud_entities);
break;
case "LR":
LazyRead(ef_crud_entities);
break;
case "ER":
EagerRead(ef_crud_entities);
break;
case "U":
Update(ef_crud_entities);
break;
case "D":
Delete(ef_crud_entities);
break;
default:
break;
}
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
finally
{
Console.WriteLine("press any key");
Console.ReadKey();
}
}
}
private static void EagerRead(EF_CRUD_Entities ef_crud_entities)
{
Customer jim = ef_crud_entities.Customer.Include("Order").Include("Order.OrderDetail").Where(c => c.CustName.Equals("JimLin")).SingleOrDefault();
if (jim != null)
{
foreach (Order o in jim.Order)
{
foreach (OrderDetail od in o.OrderDetail)
{
Console.WriteLine(od.ItemName);
}
}
}
}
private static void LazyRead(EF_CRUD_Entities ef_crud_entities)
{
int n = 0;
Customer jim = ef_crud_entities.Customer.FirstOrDefault(c => c.CustName.Equals("JimLin"));
n += 1;
foreach (Order o in jim.Order)
{
n += 1;
foreach (OrderDetail od in o.OrderDetail)
{
Console.WriteLine(od.ItemName);
}
}
Console.WriteLine("n+1 problem " + n);
}
private static void Create(EF_CRUD_Entities ef_crud_entities)
{
Customer larry = new Customer {
CustName = "LarrySU", Created = System.DateTime.Now, Modified = System.DateTime.Now
};
ef_crud_entities.Customer.Add(larry);
Order order = new Order {
CustId = larry.Id, IsExpress = true, Created = System.DateTime.Now, Modified = System.DateTime.Now
};
ef_crud_entities.Order.Add(order);
OrderDetail order_detail = new OrderDetail {
OrderId = order.Id, ItemName = "蒜頭", Count = 2, Created = System.DateTime.Now, Modified = System.DateTime.Now
};
ef_crud_entities.OrderDetail.Add(order_detail);
ef_crud_entities.SaveChanges();
}
