package Hibernate.test.hql;

import org.Hibernate.entity.Person;
import org.Hibernate.utils.HibernateUtils;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.query.Query;
import org.junit.jupiter.api.Test;

import java.util.List;

public class selectGroud {
    SessionFactory sessionFactory = null ;
    Session session = null ;
    Transaction transaction = null ;
    @Test
    public void Selectgroud(){
        try {
            sessionFactory = HibernateUtils.getSessionFactory();
            session = sessionFactory.openSession();
            transaction = session.beginTransaction();
            //创建一个query对象后，写 select 聚合函数(*) from 实体类
            Query query = session.createQuery("select count(*) from Person");
//            因为只会有一个结果返回，所以用的query.uniqueResult()方法获取一个对象
//            当然也可以用list
            Object obj = query.uniqueResult();
            System.out.println(obj);
            transaction.commit();
        } catch (Exception e) {
            e.printStackTrace();
            transaction.rollback();
        } finally {
            session.close();
            sessionFactory.close();
        }
    }
}