Criteria连接查询，不能用别名

a249786607 2016-07-09 05:58:48

package dao;





import java.util.List;

import java.util.Set;



import org.hibernate.Criteria;

import org.hibernate.Transaction;



import org.hibernate.criterion.Restrictions;



import Util.HibernateUtil;

import pojo.Dept;

import pojo.Emp;





public class DeptDao{

	/*

	 * 查找部门，通过员工人数

	 */

	public void findDeptByEmpCounts(){

		Criteria criteria = HibernateUtil.getSession().createCriteria(Dept.class,"d")

		.createCriteria("d.emps","e").add(Restrictions.sizeGe("e", 6));//创建连接

		//criteria.add(Restrictions.sizeGe("d.emps", 6));//dept 中EMP数量大于6 的dept

		List<Dept> depts = criteria.list();

		for(Dept dept:depts){

			System.out.println("============================================================");

			System.out.println("部门名称======》"+dept.getDname());

			Set<Emp> emps = dept.getEmps();

			for(Emp emp:emps){

				System.out.println("员工姓名=======》"+emp.getEname());

			}

			System.out.println("============================================================");

		}

	

	}

	public static void main(String[] args) {

		// TODO Auto-generated method stub

		Transaction transaction = HibernateUtil.getSession().beginTransaction();

		DeptDao d = new DeptDao();

		d.findDeptByEmpCounts();

	}

}

主查询容器 Dept.class的别名"d"，可以用，添加查询条件后，后面连接的emps的别名e，就不能用，直接报错

Exception in thread "main" org.hibernate.MappingException: Unknown collection role: pojo.Emp.e

	at org.hibernate.impl.SessionFactoryImpl.getCollectionPersister(SessionFactoryImpl.java:636)

	at org.hibernate.criterion.SizeExpression.toSqlString(SizeExpression.java:60)

	at org.hibernate.loader.criteria.CriteriaQueryTranslator.getWhereCondition(CriteriaQueryTranslator.java:357)

	at org.hibernate.loader.criteria.CriteriaJoinWalker.<init>(CriteriaJoinWalker.java:113)

	at org.hibernate.loader.criteria.CriteriaJoinWalker.<init>(CriteriaJoinWalker.java:82)

	at org.hibernate.loader.criteria.CriteriaLoader.<init>(CriteriaLoader.java:91)

	at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1578)

	at org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:306)

	at org.hibernate.impl.CriteriaImpl$Subcriteria.list(CriteriaImpl.java:481)

	at dao.DeptDao.findDeptByEmpCounts(DeptDao.java:27)

	at dao.DeptDao.main(DeptDao.java:43)

如果将查询条件改成下面注释的//criteria.add(Restrictions.sizeGe("d.emps", 6));直接用d.emps，就不报错，能输出结果
为何？？？？

...全文