private static void AddRecords()
{
Console.WriteLine(nameof(AddRecords));
try
{
using (var context = new MenusContext())
{
var soupCard = new MenuCard();
Menu[] soups =
{
new Menu
{
Text = "Consommé Célestine (with shredded pancake)",
Price = 4.8m,
MenuCard = soupCard
},
new Menu
{
Text = "Baked Potato Soup",
Price = 4.8m,
MenuCard = soupCard
},
new Menu
{
Text = "Cheddar Broccoli Soup",
Price = 4.8m,
MenuCard = soupCard
},
};
soupCard.Title = "Soups";
//soups会插入到Menus表
soupCard.Menus.AddRange(soups);
//soupCard插入到MenuCards表
context.MenuCards.Add(soupCard);
ShowState(context);
int records = context.SaveChanges();
Console.WriteLine($"{records} added");
Console.WriteLine();
}
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
Console.WriteLine();
}
static void UpdateUntracked(Menu m)
{
using (var context = new MenusContext())
{
ShowState(context);
//显示的关联对象到上下文
//EntityEntry<Menu> entry = context.Menus.Attach(m);
//设置对象状态是Modified
//entry.State = EntityState.Modified;
//使用Update方法可以完成关联到上下文并设置对象状态为Modified
context.Menus.Update(m);
ShowState(context);
context.SaveChanges();
}
}
private static void UpdateRecords()
{
Console.WriteLine(nameof(UpdateRecords));
using (var context = new MenusContext())
{
Menu menu = context.Menus
.Skip(1)
.FirstOrDefault();
ShowState(context); //Unchanged
menu.Price += 0.2m;
ShowState(context); //Modified
int records = context.SaveChanges();
Console.WriteLine($"{records} updated");
ShowState(context); //Unchanded
}
Console.WriteLine();
}
static void AddHundredRecords()
{
Console.WriteLine(nameof(AddHundredRecords));
using (var context = new MenusContext())
{
var card = context.MenuCards.FirstOrDefault();
if (card != null)
{
var menus = Enumerable.Range(1, 100).Select(x => new Menu
{
MenuCard = card,
Text = $"$menu {x}",
Price = 9.9m
});
//这是一个批处理，一次性插入100条数据
context.Menus.AddRange(menus);
Stopwatch stopwatch = Stopwatch.StartNew();
int record = context.SaveChanges();
stopwatch.Stop();
Console.WriteLine($"{record} records added after ${stopwatch.ElapsedMilliseconds} ms");
}
}
}
