Hiberante(八) Hql查询

常见Hql查询

	 @Test
	 public void test01(){
		 Session session =null;
		 try {
			session = HibernateUtil.openSession();
			
			/**
			 * 对于HQL而言，都是基于对象进行查询的
			 */
			Query query=session.createQuery("from Special");
			List<Special> list=query.list();
            for(Special s:list){
            	System.out.println(s.getName()+"..."+s.getType());
            }
		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			if(session!=null) session.close();
		}
		 
	 }
	 @Test
	 public void test02(){
		 Session session =null;
		 try {
			session = HibernateUtil.openSession();
			//List<Special> list=session.createQuery("select * from Special ") 不能写*
			/**
			 *  可以使用链式查询方式
			 */
			List<Special> list=session.createQuery("select spe from Special spe")
					.list();
            for(Special s:list){
            	System.out.println(s.getName()+"..."+s.getType());
            }
		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			if(session!=null) session.close();
		}
		 
	 }
	 
	 /**
	  * 
	  * @Title:  使用HQL 加条件查询 
	  * @Description:
	  * @param  
	  * @return void    返回类型 
	  * @throws
	  */
	 @Test
	 public void test03(){
		 Session session =null;
		 try {
			session=HibernateUtil.openSession();
		    List<Student> list=session.createQuery("from Student where name like '%张%' ")
		    		.list();
		    for(Student s:list){
		    	System.out.println(s.getName()+" "+s.getSex());
		    }
		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			if(session!=null) session.close();
		}
		 
	 }
	 /**
	  * 
	  * @Title:  使用HQL 加条件查询   ? 的方式
	  * @Description:
	  * @param  
	  * @return void    返回类型 
	  * @throws
	  */
	 @Test
	 public void test04(){
		 Session session =null;
		 try {
			session=HibernateUtil.openSession();
			/**
			 * 基于?的条件的查询，特别注意：jdbc设置参数的最小下标是1,hibernate 是0
			 */
		    List<Student> list=session.createQuery("from Student where name like ? ")
		    		.setParameter(0, "%李%").list();
		    for(Student s:list){
		    	System.out.println(s.getName()+" "+s.getSex());
		    }
		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			if(session!=null) session.close();
		}
		 
	 }
	 /**
	  * 
	  * @Title: test05 
	  * @Description: 基于别名进行查询  
	  * @param  
	  * @return void    返回类型 
	  * @throws
	  */
	 @Test
	 public void test05(){
		 Session session =null;
		 try {
			session=HibernateUtil.openSession();
			/**
			 * 基于?的条件的查询，特别注意：jdbc设置参数的最小下标是1,hibernate 是0
			 */
		    List<Student> list=session.createQuery("from Student where name like :name and sex=:sex ")
		    		.setParameter("name", "%李%")
		    		.setParameter("sex","男")
		    		.list();
		    for(Student s:list){
		    	System.out.println(s.getName()+" "+s.getSex());
		    }
		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			if(session!=null) session.close();
		}
		 
	 }
		@Test
		public void test06() {
			Session session = null;
			try {
				session = HibernateUtil.openSession();
				/**
				 * 使用uniqueResult可以返回唯一的一个值
				 */
				Long stus = (Long)session.createQuery("select count(*) from Student where name like :name and sex=:sex")
											.setParameter("name", "%刘%")
											.setParameter("sex", "男")
											.uniqueResult();
				System.out.println(stus);
			} catch (Exception e) {
				e.printStackTrace();
			} finally {
				HibernateUtil.close(session);
			}
		}
		
		@Test
		public void test07() {
			Session session = null;
			try {
				session = HibernateUtil.openSession();
				/**
				 * 使用uniqueResult可以返回唯一的一个值
				 */
				Student stu = (Student)session.createQuery("select stu from Student stu where id=:id")
											.setParameter("id", 1)
											.uniqueResult();
				System.out.println(stu.getName());
			} catch (Exception e) {
				e.printStackTrace();
			} finally {
				HibernateUtil.close(session);
			}
		}
		
		@Test
		public void test08() {
			Session session = null;
			try {
				session = HibernateUtil.openSession();
				/**
				 * 基于投影的查询，通过在列表中存储一个对象的数组
				 */
				List<Object[]> stus = session.createQuery("select stu.sex,count(*) from Student stu group by stu.sex")
											.list();
				for(Object[] obj:stus) {
					System.out.println(obj[0]+":"+obj[1]);
				}
			} catch (Exception e) {
				e.printStackTrace();
			} finally {
				HibernateUtil.close(session);
			}
		}
		
		@Test
		public void test09() {
			Session session = null;
			try {
				session = HibernateUtil.openSession();
				/**
				 * 如果对象中相应的导航对象，可以直接导航完成查询
				 */
				List<Student> stus = session.createQuery("select stu from Student stu where stu.classroom.name=? and stu.name like ?")
									.setParameter(0, "计算机教育班").setParameter(1, "%张%")
									.list();
				for(Student stu:stus) {
					System.out.println(stu.getName());
				}
			} catch (Exception e) {
				e.printStackTrace();
			} finally {
				HibernateUtil.close(session);
			}
		}
		
		@Test
		public void test10() {
			Session session = null;
			try {
				session = HibernateUtil.openSession();
				/**
				 * 可以使用in来设置基于列表的查询，此处的查询需要使用别名进行查询
				 * 特别注意，使用in的查询必须在其他的查询之后
				 */
				List<Student> stus = session.createQuery("select stu from Student stu where stu.name like ? and stu.classroom.id in (:clas)")
									.setParameter(0, "%张%").setParameterList("clas", new Integer[]{1,2})
									.list();
				for(Student stu:stus) {
					System.out.println(stu.getName());
				}
			} catch (Exception e) {
				e.printStackTrace();
			} finally {
				HibernateUtil.close(session);
			}
		}
		
		@Test
		public void test11() {
			Session session = null;
			try {
				session = HibernateUtil.openSession();
				/**
				 * 使用setFirstResult和setMaxResult可以完成分页的offset和pageSize的设置
				 */
				List<Student> stus = session.createQuery("select stu from Student stu where stu.classroom.id in (:clas)")
									.setParameterList("clas", new Integer[]{1,2})
									.setFirstResult(0).setMaxResults(15)
									.list();
				for(Student stu:stus) {
					System.out.println(stu.getName());
				}
			} catch (Exception e) {
				e.printStackTrace();
			} finally {
				HibernateUtil.close(session);
			}
		}
		
		@Test
		public void test12() {
			Session session = null;
			try {
				session = HibernateUtil.openSession();
				/**
				 * 可以通过is null来查询为空的对象,和sql一样不能使用=来查询null的对象
				 */
				List<Student> stus = session.createQuery("select stu from Student stu where stu.classroom is null")
									.setFirstResult(0).setMaxResults(15)
									.list();
				for(Student stu:stus) {
					System.out.println(stu.getName());
				}
			} catch (Exception e) {
				e.printStackTrace();
			} finally {
				HibernateUtil.close(session);
			}
		}
		
		@Test
		public void test13() {
			Session session = null;
			try {
				session = HibernateUtil.openSession();
				/**
				 * 使用对象的导航可以完成连接，但是是基于Cross JOIN(全连接)，效率不高，可以直接使用JOIN来完成连接
				 */
				List<Student> stus = session
						.createQuery("select stu from Student stu left join stu.classroom cla where cla.id=2")
						.setFirstResult(0).setMaxResults(15)
						.list();
				for(Student stu:stus) {
					System.out.println(stu.getName());
				}
			} catch (Exception e) {
				e.printStackTrace();
			} finally {
				HibernateUtil.close(session);
			}
		}
		
		@Test
		public void test14() {
			Session session = null;
			try {
				session = HibernateUtil.openSession();
		        //基于班级进行统计每个班男女生人数
				List<Object[]> stus=session.createQuery("select c.name,s.sex,count(s.id)  from Student s right join s.classroom c  group by c.id,s.sex").list();
				for(Object[] stu:stus){
					System.out.println(stu[0]+" "+stu[1] +stu[2]);
				}
			    
			} catch (Exception e) {
				e.printStackTrace();
			} finally {
				HibernateUtil.close(session);
			}
		}
		
		@Test
		public void test15() {
			Session session = null;
			try {
				session = HibernateUtil.openSession();
				/**
				 * 直接可以使用new XXObject完成查询，注意，一定要加上Object的完整包名
				 * 这里使用的new XX，必须在对象中加入相应的构造函数
				 */
				List<StudentDto> stus = session
						.createQuery("select new org.th.dto.StudentDto" +
								"(stu.id as sid,stu.name as sname,stu.sex as sex,cla.name as cname,spe.name as spename) " +
								"from Student stu left join stu.classroom cla left join cla.special spe")
						.list();
				for(StudentDto stu:stus) {
					System.out.println(stu.getSid()+","+stu.getSname()+","+stu.getSex()+","+stu.getCname()+","+stu.getSpename());
				}
			} catch (Exception e) {
				e.printStackTrace();
			} finally {
				HibernateUtil.close(session);
			}
		}

  StudentDto.java(数据传输对象)

 

/**
 * DTO对象没有存储的意义，仅仅是用来进行数据的传输的
 * @author Administrator
 *
 */
public class StudentDto {
	private int sid;
	private String sname;
	private String sex;
	private String cname;
	private String spename;
}