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 }

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 }

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");
}