Hibernate_查询_HQL详解（三）_命名的查询、更新与删除的HQL语法

	1，聚集函数
	2，分组
	3，连接查询 / HQL是面向对象的查询
		数据库中查询：
			select e.id_, e.name_, d.name_ from employee e inner join department d on e.departmentId=d.id_;(内连接)
			select e.id_, e.name_, d.name_ from employee e left outer join department d on e.departmentId=d.id_;(左外连接)
			select e.id_, e.name_, d.name_ from employee e right outer join department d on e.departmentId=d.id_;(右外连接)
	4，查询时使用参数
		>> 方式一：使用'?'占位
		>> 方式二：使用变量名
// 使用HQL查询
	@Test
	public void testHql2() throws Exception {
		Session session = sessionFactory.openSession();
		Transaction tx = null;
		try {
			tx = session.beginTransaction();
			// ------------------------------------
			String hql = null;//

			// 1，聚集函数：count(),max(),min(),avg(),sum()
			// 总数、最大、最小、平均、求和
			// hql = "select count(e) from Employee e";// 返回的结果是Long型的
			// hql = "select min(e.id) from Employee e";// 返回的结果是id的属性的类型
			// Long result = (Long) session.createQuery(hql).uniqueResult();
			// Number result = (Number) session.createQuery(hql).uniqueResult();
			// System.out.println("总记录数：" + result.intValue());

			// 2，分组：Group By ... Having
			// hql = "select e.name,count(*) from Employee e group by e.name";
			// hql = "select e.name,count(*) from Employee e group by e.name Having count(e.id)>1";
			// hql = "select e.name,count(*) from Employee e where e.id<9 group by e.name  Having count(e.id)>1";
			// hql = "select e.name,count(*) " + //
			// ---
			// "from Employee e " + //
			// "where e.id<9 " + //
			// "group by e.name  " + //
			// "Having count(e.id)>1 " + //
			// "order by count(e.id) asc";
			// ---
			// hql = "select e.name,count(*) as c " + //
			// "from Employee e " + //
			// "where e.id<9 " + //
			// "group by e.name  " + //
			// "Having count(e.id)>1 " + // 在Having子句中不能使用列别名
			// "Order by c asc";// 在Order by中可以使用列别名

			// 3，连接查询 / HQL是面向对象的查询
			// >> 内连接(inner关键字可以省略)
			// hql = "select e.id,e.name,d.name from Employee e join e.department d";
			// hql = "select e.id,e.name,d.name from Employee e inner join e.department d";
			// >> 左外连接(outer关键可以省略)
			// hql = "select e.id,e.name,d.name from Employee e left outer join e.department d";
			// >> 右外连接(outer关键可以省略)
			// hql = "select e.id,e.name,d.name from Employee e right outer join e.department d";

			// 可以使过更方便的方法
			// hql = "select e.id,e.name,e.department.name from Employee e";

			// 4，查询时使用参数
			// >> 方式一：使用'?'占位
			// hql = "from Employee e where e.id between ? And ?";
			// List

		1，聚集函数
		2，分组
		3，连接查询 / HQL是面向对象的查询
			数据库中查询：
				select e.id_, e.name_, d.name_ from employee e inner join department d on e.departmentId=d.id_;(内连接)
				select e.id_, e.name_, d.name_ from employee e left outer join department d on e.departmentId=d.id_;(左外连接)
				select e.id_, e.name_, d.name_ from employee e right outer join department d on e.departmentId=d.id_;(右外连接)
		4，查询时使用参数
			>> 方式一：使用'?'占位
			>> 方式二：使用变量名
		5，使用命名查询
		6，update与delete，不会通知Session缓存
			在update或delete后，需要refresh(obj)一下以获取最新的状态

			隔离级别中文			隔离级别英文				对应的整数表示
			读未提交				READ UNCOMMITED				1
			读已提交				READ COMMITED				2
			可重复读				REPEATABLE READ				4
			串行化(不可并发)		SERIALIZEABLE				8

	
	
		
			
		
		

		
		
	

	
	
		=:idMin and e.id<=:idMax
		]]>
	

	// 使用HQL查询
	@Test
	public void testHql2() throws Exception {
		Session session = sessionFactory.openSession();
		Transaction tx = null;
		try {
			tx = session.beginTransaction();
			// ------------------------------------
			String hql = null;//

			// 1，聚集函数：count(),max(),min(),avg(),sum()
			// 总数、最大、最小、平均、求和
			// hql = "select count(e) from Employee e";// 返回的结果是Long型的
			// hql = "select min(e.id) from Employee e";// 返回的结果是id的属性的类型
			// Long result = (Long) session.createQuery(hql).uniqueResult();
			// Number result = (Number) session.createQuery(hql).uniqueResult();
			// System.out.println("总记录数：" + result.intValue());

			// 2，分组：Group By ... Having
			// hql = "select e.name,count(*) from Employee e group by e.name";
			// hql = "select e.name,count(*) from Employee e group by e.name Having count(e.id)>1";
			// hql = "select e.name,count(*) from Employee e where e.id<9 group by e.name  Having count(e.id)>1";
			// hql = "select e.name,count(*) " + //
			// ---
			// "from Employee e " + //
			// "where e.id<9 " + //
			// "group by e.name  " + //
			// "Having count(e.id)>1 " + //
			// "order by count(e.id) asc";
			// ---
			// hql = "select e.name,count(*) as c " + //
			// "from Employee e " + //
			// "where e.id<9 " + //
			// "group by e.name  " + //
			// "Having count(e.id)>1 " + // 在Having子句中不能使用列别名
			// "Order by c asc";// 在Order by中可以使用列别名

			// 3，连接查询 / HQL是面向对象的查询
			// >> 内连接(inner关键字可以省略)
			// hql = "select e.id,e.name,d.name from Employee e join e.department d";
			// hql = "select e.id,e.name,d.name from Employee e inner join e.department d";
			// >> 左外连接(outer关键可以省略)
			// hql = "select e.id,e.name,d.name from Employee e left outer join e.department d";
			// >> 右外连接(outer关键可以省略)
			// hql = "select e.id,e.name,d.name from Employee e right outer join e.department d";

			// 可以使过更方便的方法
			// hql = "select e.id,e.name,e.department.name from Employee e";

			// 4，查询时使用参数
			// >> 方式一：使用'?'占位
			// hql = "from Employee e where e.id between ? And ?";
			// List