Hibernate- 基本查询

01.搭建开发环境

02.基本查询

package com.gordon.test;

import java.text.DecimalFormat;
import java.util.Arrays;
import java.util.List;

import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.Test;

import com.gordon.domain.Book;
import com.gordon.utils.HibernateUtil;

public class TestDemo1 {

	/**
	 * 分组查询
	 * 查询结果：
		Hibernate:
		    select
		        publisher1_.name as col_0_0_,
		        count(*) as col_1_0_
		    from
		        t_book book0_,
		        t_publisher publisher1_
		    where
		        book0_.publisher_id=publisher1_.id
		    group by
		        book0_.publisher_id
		[电子工业出版社, 3]
		[北京大学出版社, 2]
		[人民邮电出版社, 2]
	 */
	@Test
	public void run5() {
		Session session = HibernateUtil.getCurrentSession();
		Transaction transaction = session.beginTransaction();

		List<Object[]> list = session.createQuery("select b.publisher.name, count(*) from Book b group by b.publisher").list();
		for (Object[] book : list) {
			System.out.println(Arrays.toString(book));
		}

		transaction.commit();
	}

	/**
	 * 聚合函数
	 * 查询结果：
		Hibernate:
		    select
		        count(*) as col_0_0_
		    from
		        t_book book0_
		Hibernate:
		    select
		        sum(book0_.price) as col_0_0_
		    from
		        t_book book0_
		Hibernate:
		    select
		        max(book0_.price) as col_0_0_,
		        min(book0_.price) as col_1_0_
		    from
		        t_book book0_
		Hibernate:
		    select
		        avg(book0_.price) as col_0_0_
		    from
		        t_book book0_
		count: 7
		sum: 330.04
		Max:70.00 Min:31.00
		avg: 47.15
	 */
	@Test
	public void run4() {
		Session session = HibernateUtil.getCurrentSession();
		Transaction transaction = session.beginTransaction();

		String count = "select count(*) from Book";
		Long c = (Long) session.createQuery(count).uniqueResult();

		String sum = "select sum(b.price) from Book b";
		Double s = (Double) session.createQuery(sum).uniqueResult();

		String maxmin = "select max(b.price), min(b.price) from Book b";
		Object[] mm = (Object[]) session.createQuery(maxmin).uniqueResult();

		String avg = "select avg(b.price) from Book b";
		Double a = (Double) session.createQuery(avg).uniqueResult();

		DecimalFormat df = new DecimalFormat("00.00");

		System.out.println("count: " + c);
		System.out.println("sum: " + df.format(s));
		System.out.println("Max:" + df.format(mm[0]) + " Min:" + df.format(mm[1]));
		System.out.println("avg: " + df.format(a));

		transaction.commit();
	}

	/**
	 * 检索图书对象的部分属性
	 * 查询结果
		Hibernate:
		    select
		        book0_.name as col_0_0_,
		        book0_.price as col_1_0_
		    from
		        t_book book0_
		    order by
		        book0_.price desc
		[云计算技术及性能优化, 70.0]
		[架构探险：轻量级微服务架构（下册）, 63.2]
		[中国冰雪梦, 54.0]
		[生产微服务 , 44.0]
		[VisualBasic2015实践教程 , 36.0]
		[Photoshop图形图像处理, 31.84]
		[C语言程序设计, 31.0]
	 */
	@Test
	public void run3() {
		Session session = HibernateUtil.getCurrentSession();
		Transaction transaction = session.beginTransaction();

		List<Object[]> list = session.createQuery("select b.name, b.price from Book b order by b.price desc").list();
		for (Object[] book : list) {
			System.out.println(Arrays.toString(book));
		}

		transaction.commit();
	}

	/**
	 * 对查询结果进行排序
	 * 查询结果：
		Hibernate:
		    select
		        book0_.id as id1_0_,
		        book0_.name as name2_0_,
		        book0_.price as price3_0_,
		        book0_.publisher_id as publishe4_0_
		    from
		        t_book book0_
		    order by
		        book0_.price desc
		70.0, 云计算技术及性能优化
		63.2, 架构探险：轻量级微服务架构（下册）
		54.0, 中国冰雪梦
		44.0, 生产微服务
		36.0, VisualBasic2015实践教程
		31.84, Photoshop图形图像处理
		31.0, C语言程序设计
	 */
	@Test
	public void run2() {
		Session session = HibernateUtil.getCurrentSession();
		Transaction transaction = session.beginTransaction();

		List<Book> list = session.createQuery("from Book b order by b.price desc").list();
		for (Book book : list) {
			System.out.println(book.getPrice() + ", " + book.getName());
		}

		transaction.commit();
	}

	/**
	 * 查询所有图书
	 * 查询结果：
		Hibernate:
		    select
		        book0_.id as id1_0_,
		        book0_.name as name2_0_,
		        book0_.price as price3_0_,
		        book0_.publisher_id as publishe4_0_
		    from
		        t_book book0_
		云计算技术及性能优化
		C语言程序设计
		中国冰雪梦
		Photoshop图形图像处理
		VisualBasic2015实践教程
		生产微服务
		架构探险：轻量级微服务架构（下册）
	 */
	@Test
	public void run1() {
		Session session = HibernateUtil.getCurrentSession();
		Transaction transaction = session.beginTransaction();

		List<Book> list = session.createQuery("from Book").list();
		for (Book book : list) {
			System.out.println(book.getName());
		}

		transaction.commit();
	}
}