假设你有两张桌子Movies
& Cast
(这两张桌子的图片都在下面给出)--->
![在此处输入图像描述](https://i.stack.imgur.com/KbEMY.png)
现在你想使用 MovieId 访问 Cast 的数据(Cast.MovieId 是 Movies_tbl.id 的 FK)而不是 Linq 将是--->
private static void ShowCast(MoviesEntities moviesEntities)
{
using (moviesEntities)
{
ShowAllMovies(moviesEntities);
Console.WriteLine("Movie id");
var id = Convert.ToInt32(Console.ReadLine());
using (var mEntities = new MoviesEntities())
{
if (mEntities.Movies_tbl.Any(x => x.id == id))
{
var Actor = mEntities.Movies_tbl.FirstOrDefault(x => x.id == id).Cast.Actor;
Console.WriteLine(Actor);
var Actoress = mEntities.Movies_tbl.FirstOrDefault(x => x.id == id).Cast.Actoress;
Console.WriteLine(Actoress);
}
}
}
}
private static void ShowAllMovies(MoviesEntities moviesEntities)
{
Console.WriteLine("movies ids");
using (moviesEntities)
{
var idList = moviesEntities.Movies_tbl.Select(x => x.id);
foreach (var idin idList )
{
Console.WriteLine(id.ToString());
}
}
}
添加对象(将记录插入数据库) --->
private static void AddMovie(MoviesEntities moviesEntities)
{
using (moviesEntities)
{
moviesEntities.Movies_tbl.AddObject(new Movies_tbl { title = "ExampleTitle", Cast = new Cast { Actor = "ExampleActor", Actoress = "ExampleActoress" } });
moviesEntities.SaveChanges();
}
}
TO UPDATE AN OBJECT(对数据库执行更新操作) --->
private static void UpdateCast(MoviesEntities moviesEntities)
{
using (moviesEntities)
{
var cast = moviesEntities.Casts.Where(x => x.MovieId == 10).Single();
cast.Actor = "UpdatedActorName";
cast.Actoress = "UpdatedActoressName";
moviesEntities.SaveChanges();
}
}
其中MoviesEntities
是带有后缀“实体”并从 ObjectContext 类派生的部分类。
.edmx
当您通过现有数据库创建时,它将自动创建