首先是WebSys实体
public class WebSys{
private Long id;
private String name;
}

其次是CompanyWebSys实体
public class CompanyWebSys{
private Long id;
@manytoone
@joinColumn(name = "websys_id")
private WebSys webSys;

@manytoone
@joinColumn(name = "website_id")
private Website website;
}

数据库中可能的数据有

webSys

id name
1 article
2 manager
3 admin

companyWebSys

id webSys_id
1 1

我现在要做的是 查出
[color=red]companyWebsys中还没有的webSys[/color]

也就是webSys中的记录2，3

我想的语句 最简单的
select bean from WebSys as bean where bean.id not in (select c.webSys.id from CompanyWebSys as c where c.website = ?)

然而 hql 不能识别companyWebsys 所以 这个不行

[quote]select bean from WebSys as bean where bean.id not in (select c.webSys.id from CompanyWebSys as c where c.website = ?) [/quote]这个不行？我从数据自己的数据库里找了两个类似的表，实体bean也一样，我用下面这种方式怎么能行？
from WebSys bean where bean.id not in (select webSys.id from CompanyWebSys c inner join c.webSys webSys)

hql与sql的区别是：
hql是对对象进行操作，sql是对数据库进行操作