dapper关联关系查询小测试

测试实体类（表结构）

public class User
{
    public int user_id { get; set; }
    public string user_name { get; set; }
}

public class Book
{
    public int book_id { get; set; }
    public string book_name { get; set; }
    public int user_id { get; set; }
}

//一对多关系
public class UserBooks : User
{
    public List<Book> Books;
    public UserBooks()
    {
        Books = new List<Book>();
    }
}

//一对一关系
public class UserBook : User
{
    public Book MyBook;
}

测试程序

    public static void TestOneToMany()
    {
        using (var con = new MySqlConnection("Server=182.180.57.3;Database=test;port=3306;user id=root;password=123;"))
        {
            Console.WriteLine("==========下面是一对多的Demo===========");
            var userBooks = con.Query<UserBooks, Book, UserBooks>(@"SELECT a.user_name,a.user_id,b.user_id,b.book_id, b.book_name FROM tab_user a INNER JOIN tab_book b ON a.user_id=b.user_id"
                , (user, book) =>
                     {
                         user.Books.Add(book);
                         return user;
                     }, null, null, true, "user_id");
            foreach (UserBooks ub in userBooks)
            {
                Console.Write(ub.user_id + "\t" + ub.user_name + "\t");
                foreach (Book book in ub.Books)
                {
                    Console.Write(book.book_id + "      " + book.book_name + "\n");
                }
            }
            Console.WriteLine("==========下面是一对一的Demo===========");
            var userBook = con.Query<UserBook, Book, UserBook>(@"SELECT a.user_name,a.user_id,b.user_id,b.book_id, b.book_name FROM tab_user a INNER JOIN tab_book b ON a.user_id=b.user_id where a.user_id=3"
                , (user, book) =>
                {
                    user.MyBook = book;
                    return user;
                }, null, null, true, "user_id").First<UserBook>();
            Console.WriteLine(userBook.user_id + "\t" + userBook.user_name + "\t" + userBook.MyBook.book_id + "\t" + userBook.MyBook.book_name);
            Console.Read();
        }
    }