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()); 

     // 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("\nIn 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().Title = "The New ADO.NET Blog";
     context.Blogs.Remove(context.Blogs.Find());
     context.Authors.Add(new Author { Name = "Jane Doe" });
     context.Readers.Find().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("\nAll 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("\nTracked 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("\nPeople: ");
 //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 = ; 

    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");
}