public class Book
    {
        public int ID;
        public string Name;
        public string Description;
        public BookComment bookComment;
        public BookPic bookPic;
    }

 

   public class BookPic
    {
        public int ID;
        public int BookID;
        public string Name;
        public string PicDesc;
    }

 

public class BookComment
    {
        public int ID;
        public int BookId;
        public string Name;
        public string Comment;
    }

查询用到splitOn，匹配是从结果列最后往前找，如下找到BookID到最后列映射到C表中，再往前找到Name，再映射到B表中，再前面的列则映射A表中，查找分隔匹配是不区分大小写的。
如果是跨库查询，配置的user需要有open其它库的权限。

       public List<Book> GetBookList()
        {
            List<Book> bList = null;
            try
            {
                using (var t = new SqlConnection(ConfigurationManager.ConnectionStrings["Test"].ConnectionString))
                {
                    bList= t.Query<Book, BookComment, BookPic, Book>(@"select
                                                                         a.ID,a.Name,a.Description,
                                                                         b.Name,b.ID,b.BookId,b.Comment,
                                                                         c.BookID,c.ID,c.Name,c.PicDesc
                                                                         from [dbo].[Book]
                                                                         a inner join [dbo].[BookComment] b on a.id=b.bookid
                                                                         inner join [dbo].[BookPic] c on a.id =c.bookid",
                                                            (book, bookcomment, bookpic) =>
                                                            {
                                                                book.bookComment = bookcomment;
                                                                book.bookPic = bookpic;
                                                                return book;
                                                            },
                                                            splitOn: "Name,BookID"
                                                            ).ToList();
                }
            }
            catch (Exception ex)
            {
                nlog.Error(ex.ToString());
            }
            return bList;
        }