hibernate 多对一 如何根据一的Id查出所有的多对象

[code="java"]
public class HrTrainType implements java.io.Serializable {
private Set hrTrainActivities = new HashSet();
}
[/code]

[code="java"]
public class HrTrainActivity implements java.io.Serializable {
private HrTrainType hrTrainType;

}

[/code]
我的hql是
[code="java"]
String hql = "from HrTrainActivity where HrTrainType= " + channelId;
[/code]
报错了。
改为
[code="java"]
String hql = "from HrTrainActivity where HrTrainType.id= " + channelId;
[/code]
也一样报错。hql是根据对象查询，第二条语句应该是错误的。

我知道了HrTrainType的id是3，怎么根据3查出HrTrainActivity 的外键channelId是3的全部数据呢？

感觉是这样的吧
[code="java"]String hql = "from HrTrainActivity where hrTrainType.id= " + channelId; [/code]

[code="java"]String hql = "from HrTrainType where id= 3";[/code] 查出HrTrainType 然后该对象的hrTrainActivities 列表里的所有HrTrainActivity 的外键，也就是HrTrainType主键 不就是3么

[code="java"]String hql = "from HrTrainActivity hr where hr.hrTrainType.id= " + channelId; [/code]