Hibernate的查询大致分为以下三种场景，
1. HQL查询-hibernate Query Language(多表查询,但不复杂时使用)
2. Criteria查询(单表条件查询)
3. 原生SQL查询(复杂的业务查询)
接下来解释三种使用方法:
1.HQL查询-hibernate Query Language(多表查询,但不复杂时使用) Hibernate独家查询语言,属于面向对象的查询语言
注意:HQL语言中不会出现SQL中的表和列，HQL使用的都是JavaBean的类名和属性名。
1.HQL基本查询
(1)查询所有的基本语句
???@Test ???// HQL查询所有数据 ???public void fun1() { ???????// 1 获得session ???????Session session = HibernateUtil.openSession(); ???????// 2.书写HQL语句 ???????String hql = "from cn.qlq.domain.Customer";// from 类名全路径 ???????// 3.根据hql创建查询对象 ???????Query query = session.createQuery(hql); ???????// 4.根据查询对象获取查询结果 ???????List<Customer> customers = query.list(); ???????System.out.println(customers); ???}结果:
Hibernate: ????select ???????customer0_.cust_id as cust_id1_0_, ???????customer0_.cust_name as cust_nam2_0_, ???????customer0_.cust_source as cust_sou3_0_, ???????customer0_.cust_industry as cust_ind4_0_, ???????customer0_.cust_level as cust_lev5_0_, ???????customer0_.cust_linkman as cust_lin6_0_, ???????customer0_.cust_phone as cust_pho7_0_, ???????customer0_.cust_mobile as cust_mob8_0_ ????from ???????cst_customer customer0_[Customer [cust_id=1, cust_name=XXXXXXXXXX], Customer [cust_id=2, cust_name=联想]]
改进:如果整个项目中只有一个类的名字可以省略包路径，也就是可以只写类名:
???@Test ???// HQL查询所有数据 ???public void fun1() { ???????// 1 获得session ???????Session session = HibernateUtil.openSession(); ???????// 2.书写HQL语句// ???????String hql = "from cn.qlq.domain.Customer";// from 类名全路径 ???????String hql = "from Customer";// 如果整个项目中只有这一个类名可以直接写名字 ???????// 3.根据hql创建查询对象 ???????Query query = session.createQuery(hql); ???????// 4.根据查询对象获取查询结果 ???????List<Customer> customers = query.list(); ???????System.out.println(customers); ???}(2)根据主键查询单个
???@Test ???// HQL查询单个数据 ???public void fun2() { ???????// 1 获得session ???????Session session = HibernateUtil.openSession(); ???????// 2.书写HQL语句// ???????String hql = "from cn.qlq.domain.Customer";// from 类名全路径 ???????String hql = "from Customer where cust_id = 1";// where后面是Customer的属性名称而不是列名 ???????// 3.根据hql创建查询对象 ???????Query query = session.createQuery(hql); ???????// 4.根据查询对象获取查询结果 ???????Customer customer = (Customer) query.uniqueResult(); ???????System.out.println(customer); ???}2.HQL条件查询:
(1)?占位符查询
类似于JDBC的占位符，只是hibernate的?下标从0开始，而JDBC的下标从1开始，基本上所有的编程索引都从0开始，唯独JDBC从1开始。。。。
???@Test ???// HQL的?占位符查询 ???public void fun3() { ???????// 1 获得session ???????Session session = HibernateUtil.openSession(); ???????// 2.书写HQL语句// ???????String hql = "from cn.qlq.domain.Customer";// from 类名全路径 ???????String hql = "from Customer where cust_id = ?";// 如果整个项目中只有这一个类名可以直接写名字 ???????// 3.根据hql创建查询对象 ???????Query query = session.createQuery(hql);// ???????query.setLong(0, 1l);//类似于JDBC的占位符，只是JDBC的占位符下标从0开始，hibernate从1开始 ???????query.setParameter(0, 1l);//这种写法不用管类型 ???????// 4.根据查询对象获取查询结果 ???????Customer customer = (Customer) query.uniqueResult(); ???????System.out.println(customer); ???}(2)命令占位符 ：name格式的查询，固定格式，name随便起，习惯性的起做和条件名字一样
???@Test ???// HQL的命令占位符查询 ???public void fun4() { ???????// 1 获得session ???????Session session = HibernateUtil.openSession(); ???????// 2.书写HQL语句// ???????String hql = "from cn.qlq.domain.Customer";// from 类名全路径 ???????String hql = "from Customer where cust_id = :cust_id";// :cust_id的名字随便起，只不过习惯性的起做一样 ???????// 3.根据hql创建查询对象 ???????Query query = session.createQuery(hql);// ???????query.setLong(0, 1l);//类似于JDBC的占位符，只是JDBC的占位符下标从0开始，hibernate从1开始 ???????query.setParameter("cust_id",1l); ???????// 4.根据查询对象获取查询结果 ???????Customer customer = (Customer) query.uniqueResult(); ???????System.out.println(customer); ???}3.HQL分页查询
分页查询类似于mysql的limit关键字，limit start，pageSize。。。。。。
???@Test ???// HQL分页查询 ???public void fun5() { ???????// 1 获得session ???????Session session = HibernateUtil.openSession(); ???????// 2.书写HQL语句// ???????String hql = "from cn.qlq.domain.Customer";// from 类名全路径 ???????String hql = "from Customer";// :cust_id的名字随便起，只不过习惯性的起做一样 ???????// 3.根据hql创建查询对象 ???????Query query = session.createQuery(hql); ???????/** ????????* 类似于 limit start,pageSize; ????????* 假设页大小是2 ????????* 页号 起始值 ?页大小 ????????* 1 ??0 ???2 ????????* 2 ??2 ???2 ????????*/ ???????//例如取第二页数据 ???????query.setFirstResult(2); ???????query.setMaxResults(2); ???????// 4.根据查询对象获取查询结果 ????????List<Customer> customers = query.list(); ???????System.out.println(customers); ???}结果:
Hibernate: ????select ???????customer0_.cust_id as cust_id1_0_, ???????customer0_.cust_name as cust_nam2_0_, ???????customer0_.cust_source as cust_sou3_0_, ???????customer0_.cust_industry as cust_ind4_0_, ???????customer0_.cust_level as cust_lev5_0_, ???????customer0_.cust_linkman as cust_lin6_0_, ???????customer0_.cust_phone as cust_pho7_0_, ???????customer0_.cust_mobile as cust_mob8_0_ ????from ???????cst_customer customer0_ limit ?, ????????[Customer [cust_id=3, cust_name=博客园], Customer [cust_id=4, cust_name=仍然]]
2.Criteria查询(单表条件查询)
Hibernate的批量查询
原文地址：https://www.cnblogs.com/qlqwjy/p/9357369.html