Hibernate聚集函数

快来打我* 2022-05-24 11:17 155阅读 0赞

##### 【例】雇员信息表 #####

![2018052608291149][]

##### 统计雇员人数(count) #####

session=HibernateSessionFactory.getSession();
    			String hql="select count(emp) from Employee emp";
    			Query query=session.createQuery(hql);
    			long count=(long)query.uniqueResult();									
    			System.out.println("雇员人数："+count);

运行结果：

![20180526083329311][]

##### 计算雇员平均薪资(avg) #####

session=HibernateSessionFactory.getSession();
    			String hql="select avg(emp.emp_salary) from Employee emp";
    			Query query=session.createQuery(hql);
    			double avg=(double)query.uniqueResult();									
    			System.out.println("平均薪资："+avg);

运行结果：

![20180526084833173][]

##### 薪资(sum) #####

session=HibernateSessionFactory.getSession();
    			String hql="select sum(emp.emp_salary) from Employee emp";
    			Query query=session.createQuery(hql);
    			double sum=(double)query.uniqueResult();									
    			System.out.println("薪资："+sum);

运行结果：

![2018052608410879][]

##### 最高薪资(max) #####

session=HibernateSessionFactory.getSession();
    			String hql="select max(emp.emp_salary) from Employee emp";
    			Query query=session.createQuery(hql);
    			double max=(double)query.uniqueResult();									
    			System.out.println("最高薪资："+max);

运行结果:

![20180526084309351][]

##### 最低薪资(min) #####

session=HibernateSessionFactory.getSession();
    			String hql="select min(emp.emp_salary) from Employee emp";
    			Query query=session.createQuery(hql);
    			double min=(double)query.uniqueResult();									
    			System.out.println("最低薪资："+min);

运行结果：

![20180526084450631][]

[2018052608291149]: /images/20220524/aaa167dd006645b6be10f68f8751d860.png
[20180526083329311]: /images/20220524/05efe3953e2b4a4e9a53b67e848fb9c1.png
[20180526084833173]: /images/20220524/083bfb07940c447b9db3e8b1d3698abf.png
[2018052608410879]: /images/20220524/70a7ec4635564f818a5dd4c9ece5da03.png
[20180526084309351]: /images/20220524/fc1ecff1a10b47dd91160878bf234675.png
[20180526084450631]: /images/20220524/4949f2da945a459aba1f82eee9167152.png