Entity Framework 学习 Model First

本篇主要写写Model First

首先建立一个数据库，数据库名称为blog，然后创建一个可控制台应用程序，添加ADO.NET 实体数据模型

点击添加

 选择空模型，点击完成，生成Blog.edmx

空白处右键添加实体Blog

更改属性设置

依次添加User、Post、Comment实体

添加关联

注意导航属性的对应关系

生成数据库，空白处右键，更具模型生成数据库

执行sql语句生成表

测试代码

using (BlogContainer db = new BlogContainer())
{
    db.Users.AddObject(new User { Name = "ian.w" });
    db.Users.AddObject(new User { Name = "whxwchg" });
    db.Users.AddObject(new User { Name = "hzd" });
    db.SaveChanges();
    db.Blogs.AddObject(new Blog { BlogName = "ian.w的博客", BlogUrl = "http://whx1973.cnblogs.com", User = db.Users.FirstOrDefault()});
    db.Blogs.AddObject(new Blog { BlogName = "hzd的博客", BlogUrl = "http://hzd.cnblogs.com", User = db.Users.Where(user => user.ID == 2).Select(user => user).First() });
    db.SaveChanges();
    db.Posts.AddObject(new Post { Title = "entity framework database first", User = db.Users.FirstOrDefault() });
    db.Posts.AddObject(new Post { Title = "entity framework model first", User = db.Users.FirstOrDefault() });
    db.Posts.AddObject(new Post { Title = "linq to object", User = db.Users.Where(user => user.ID == 2).Select(user => user).First() });
    db.SaveChanges();
   

    db.Comments.AddObject(new Comment { Content = "tks", User = db.Users.Where(user => user.ID == 1).Select(user => user).First(), Post = db.Posts.First() });
    db.SaveChanges();
}