EF中执行原生sql与使用Local获取本地数据

使用DbSet的Local属性可以访问当前context中被追踪且没有被标记为删除的实体(内存中的数据)

 1 using (var context = new BloggingContext()) 

 2 { 

 3     // Load all blogs from the database into the context 

 4     context.Blogs.Load(); 

 5  

 6     // Add a new blog to the context 

 7     context.Blogs.Add(new Blog { Name = "My New Blog" }); 

 8  

 9     // Mark one of the existing blogs as Deleted 

10     context.Blogs.Remove(context.Blogs.Find(1)); 

11  

12     // Loop over the blogs in the context. 

13     Console.WriteLine("In Local: "); 

14     foreach (var blog in context.Blogs.Local) 

15     { 

16         Console.WriteLine( 

17             "Found {0}: {1} with state {2}", 

18             blog.BlogId,  

19             blog.Name, 

20             context.Entry(blog).State); 

21     } 

22  

23     // Perform a query against the database. 

24     Console.WriteLine("\nIn DbSet query: "); 

25     foreach (var blog in context.Blogs) 

26     { 

27         Console.WriteLine( 

28             "Found {0}: {1} with state {2}", 

29             blog.BlogId,  

30             blog.Name, 

31             context.Entry(blog).State); 

32     } 

33 }

View Code

获取追踪对象的详细信息

 1 using (var context = new BloggingContext()) 

 2 { 

 3     // Load some entities into the context 

 4     context.Blogs.Load(); 

 5     context.Authors.Load(); 

 6     context.Readers.Load(); 

 7  

 8     // Make some changes 

 9     context.Blogs.Find(1).Title = "The New ADO.NET Blog"; 

10     context.Blogs.Remove(context.Blogs.Find(2)); 

11     context.Authors.Add(new Author { Name = "Jane Doe" }); 

12     context.Readers.Find(1).Username = "johndoe1987"; 

13  

14     // Look at the state of all entities in the context 

15     Console.WriteLine("All tracked entities: "); 

16     foreach (var entry in context.ChangeTracker.Entries()) 

17     { 

18         Console.WriteLine( 

19             "Found entity of type {0} with state {1}", 

20             ObjectContext.GetObjectType(entry.Entity.GetType()).Name, 

21             entry.State); 

22     } 

23  

24     // Find modified entities of any type 

25     Console.WriteLine("\nAll modified entities: "); 

26     foreach (var entry in context.ChangeTracker.Entries() 

27                               .Where(e => e.State == EntityState.Modified)) 

28     { 

29         Console.WriteLine( 

30             "Found entity of type {0} with state {1}", 

31             ObjectContext.GetObjectType(entry.Entity.GetType()).Name, 

32             entry.State); 

33     } 

34  

35     // Get some information about just the tracked blogs 

36     Console.WriteLine("\nTracked blogs: "); 

37     foreach (var entry in context.ChangeTracker.Entries<Blog>()) 

38     { 

39         Console.WriteLine( 

40             "Found Blog {0}: {1} with original Name {2}", 

41             entry.Entity.BlogId,  

42             entry.Entity.Name, 

43             entry.Property(p => p.Name).OriginalValue); 

44     } 

45  

46     // Find all people (author or reader) 

47     Console.WriteLine("\nPeople: "); 

48 //返回所有实现IPerson接口的类的Name属性值

49     foreach (var entry in context.ChangeTracker.Entries<IPerson>()) 

50     { 

51         Console.WriteLine("Found Person {0}", entry.Entity.Name); 

52     } 

53 }

54 

55 

56 public class Author : IPerson 

57 { 

58     public int AuthorId { get; set; } 

59     public string Name { get; set; } 

60     public string Biography { get; set; } 

61 } 

62  

63 public class Reader : IPerson 

64 { 

65     public int ReaderId { get; set; } 

66     public string Name { get; set; } 

67     public string Username { get; set; } 

68 } 

69  

70 public interface IPerson 

71 { 

72     string Name { get; } 

73 }

View Code

 

EF中执行原生的sql语句

1.在指定实体上进行查询

using (var context = new BloggingContext()) 

{ 

    var blogs = context.Blogs.SqlQuery("SELECT * FROM dbo.Blogs").ToList(); 

}

2.执行存储过程 

using (var context = new BloggingContext()) 

{ 

    var blogs = context.Blogs.SqlQuery("dbo.GetBlogs").ToList(); 

}



//带参数的存储过程

using (var context = new BloggingContext()) 

{ 

    var blogId = 1; 

 

    var blogs = context.Blogs.SqlQuery("dbo.GetBlogById @p0", blogId).Single(); 

}

3.执行sql命令

using (var context = new BloggingContext()) 

{ 

    var blogNames = context.Database.SqlQuery<string>( 

                       "SELECT Name FROM dbo.Blogs").ToList(); 

}



using (var context = new BloggingContext()) 

{ 

    context.Database.SqlCommand( 

        "UPDATE dbo.Blogs SET Name = 'Another Name' WHERE BlogId = 1"); 

}