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)

using (var context = new BloggingContext()) 
{ 
    // Load all blogs from the database into the context 
    context.Blogs.Load(); 
 
    // Add a new blog to the context 
    context.Blogs.Add(new Blog { Name = "My New Blog" }); 
 
    // Mark one of the existing blogs as Deleted 
    context.Blogs.Remove(context.Blogs.Find(1)); 
 
    // Loop over the blogs in the context. 
    Console.WriteLine("In Local: "); 
    foreach (var blog in context.Blogs.Local) 
    { 
        Console.WriteLine( 
            "Found {0}: {1} with state {2}", 
            blog.BlogId,  
            blog.Name, 
            context.Entry(blog).State); 
    } 
 
    // Perform a query against the database. 
    Console.WriteLine("
In DbSet query: "); 
    foreach (var blog in context.Blogs) 
    { 
        Console.WriteLine( 
            "Found {0}: {1} with state {2}", 
            blog.BlogId,  
            blog.Name, 
            context.Entry(blog).State); 
    } 
}

获取追踪对象的详细信息

using (var context = new BloggingContext()) 
{ 
    // Load some entities into the context 
    context.Blogs.Load(); 
    context.Authors.Load(); 
    context.Readers.Load(); 
 
    // Make some changes 
    context.Blogs.Find(1).Title = "The New ADO.NET Blog"; 
    context.Blogs.Remove(context.Blogs.Find(2)); 
    context.Authors.Add(new Author { Name = "Jane Doe" }); 
    context.Readers.Find(1).Username = "johndoe1987"; 
 
    // Look at the state of all entities in the context 
    Console.WriteLine("All tracked entities: "); 
    foreach (var entry in context.ChangeTracker.Entries()) 
    { 
        Console.WriteLine( 
            "Found entity of type {0} with state {1}", 
            ObjectContext.GetObjectType(entry.Entity.GetType()).Name, 
            entry.State); 
    } 
 
    // Find modified entities of any type 
    Console.WriteLine("
All modified entities: "); 
    foreach (var entry in context.ChangeTracker.Entries() 
                              .Where(e => e.State == EntityState.Modified)) 
    { 
        Console.WriteLine( 
            "Found entity of type {0} with state {1}", 
            ObjectContext.GetObjectType(entry.Entity.GetType()).Name, 
            entry.State); 
    } 
 
    // Get some information about just the tracked blogs 
    Console.WriteLine("
Tracked blogs: "); 
    foreach (var entry in context.ChangeTracker.Entries<Blog>()) 
    { 
        Console.WriteLine( 
            "Found Blog {0}: {1} with original Name {2}", 
            entry.Entity.BlogId,  
            entry.Entity.Name, 
            entry.Property(p => p.Name).OriginalValue); 
    } 
 
    // Find all people (author or reader) 
    Console.WriteLine("
People: "); 
//返回所有实现IPerson接口的类的Name属性值
    foreach (var entry in context.ChangeTracker.Entries<IPerson>()) 
    { 
        Console.WriteLine("Found Person {0}", entry.Entity.Name); 
    } 
}


public class Author : IPerson 
{ 
    public int AuthorId { get; set; } 
    public string Name { get; set; } 
    public string Biography { get; set; } 
} 
 
public class Reader : IPerson 
{ 
    public int ReaderId { get; set; } 
    public string Name { get; set; } 
    public string Username { get; set; } 
} 
 
public interface IPerson 
{ 
    string Name { get; } 
}

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"); 
}