//文章

public class Post

        {

            public int ID { get; set; }

            public string Title { get; set; }

            public string Body { get; set; }

            //一篇文章只对应一个作者
            public int AuthorID{get;set;}

            public Author Author { get; set; }

        }

//作者

        public class Author

        {

            public int ID { get; set; }

            public string Name { get; set; }

        }

var data = cnn.Query<Post, Author, Post>(@"select * from Posts p left join Authors a on a.ID = p.AuthorID", (post, author) => { post.Author = author; return post; },splitOn:"ID").ToList();