这里的问题包括将用LINQ写成的语句翻译成SQL语法成NHibernate的等价物。在LINQ to SQL中的代码看起来像这样:使用NHibernate的HQL进行多个内部连接的查询
var whatevervar = from threads in context.THREADs
join threadposts in context.THREADPOSTs
on threads.thread_id equals threadposts.thread_id
join posts1 in context.POSTs
on threadposts.post_id equals posts1.post_id
join users in context.USERs
on posts1.user_id equals users.user_id
orderby posts1.post_time
where threads.thread_id == int.Parse(id)
select new
{
threads.thread_topic,
posts1.post_time,
users.user_display_name,
users.user_signature,
users.user_avatar,
posts1.post_body,
posts1.post_topic
};
它本质上是试图抓住给定的论坛主题内的职位名单。我已经能够想出(与本网站的用户有帮助的帮助下)为NHibernate的最好的是:
var whatevervar = session.CreateQuery("select t.Thread_topic, p.Post_time, " +
"u.User_display_name, u.User_signature, " +
"u.User_avatar, p.Post_body, p.Post_topic " +
"from THREADPOST tp " +
"inner join tp.Thread_ as t " +
"inner join tp.Post_ as p " +
"inner join p.User_ as u " +
"where tp.Thread_ = :what")
.SetParameter<THREAD>("what", threadid)
.SetResultTransformer(Transformers.AliasToBean(typeof(MyDTO)))
.List<MyDTO>();
但是,这并不解析很好,抱怨别名连接表是空引用。 MyDTO是输出的自定义类型:
public class MyDTO
{
public string thread_topic { get; set; }
public DateTime post_time { get; set; }
public string user_display_name { get; set; }
public string user_signature { get; set; }
public string user_avatar { get; set; }
public string post_topic { get; set; }
public string post_body { get; set; }
}
我出出主意,并同时通过直接的SQL查询这样做是可行的,我希望做正确,没有击败使用的目的ORM。
在此先感谢!
编辑:
数据库看起来是这样的:http://i41.tinypic.com/5agciu.jpg(还不能发表图片。)
奇怪的名字是由NConstruct Lite生成的XML的结果,我用它来制作ORM文件和其他东西。主键从“smth_id”更改为“Id”,外键从“smth_id”更改为“Smth_”。 – 2010-04-18 10:07:30