Entity Framework练习题

1. 问题: 变量id2的值是1，还是2? 假如如下面的注释操作，movies2有几条记录？里面会包含ID = 1的记录吗？

var id1 = db.Movies.First().ID;

var movies1 = db.Movies.ToList();

var movie = from m in db.Movies

where m.ID.Equals(1)

select m;

movie.First().ID = 2;

var id2 = db.Movies.First().ID;

//下面设置断点，运行到断点处后，手动向数据库中再添加一条记录

var movies2 = db.Movies.ToList();

2. 问题: movie2的price是多少？

 

 

 

var movie1 = db.Movies.Find(1);
movie1.Price = 100;
var movie2 = db.Movies.Find(1);

3. 下面movie1和move2的类型一样吗？User1和User2类型一样吗？

定义了下面的Model

    public class Movie
    {
        public int ID { get; set; }
        public string Title { get; set; }
        public DateTime ReleaseDate { get; set; }
        public string Genre { get; set; }
        public decimal Price { get; set; }
        public virtual Category Category { get; set; }
    }

    public class Category
    {
        public int ID { get; set; }
        public string Name { get; set; }
        public virtual ICollection<Movie> Movies { get; set; }
    }
     
    public class User
    {
        public string Name{get;set;}
    }

使用不同的方式创建Movie, User对象

var movie1 = db.Movies.Create();
var movie2 = new Movie();

var user1 = db.User.Create();
var user2 = new User();