HQL: hibernate query language（hibernate特有的查询语言）
hql是基于对象的查询语言，其语法与sql类似，但是他和sql的区别在于sql是面向表和字段的查询，而hql是面向对象和属性的查询。
需求1. 查询出所有的项目
@Test ???public void testFindAllPorject(){ ???????//获取hibernate session ???????Session session = HibernateUtils.getSession(); ???????//定义hql语句 ???????String hql = ?"select project from com.deng.hibernate.bean.Project project"; // "select * from project"; ???????//创建一个查询对象Query ???????Query query = session.createQuery(hql); ???????//调用query的相关方法来执行相关的动作 ???????List<Project> list = query.list(); ???????System.out.println(list); ???????session.close(); ???}需求2. 根据给定项目的地址模糊查询，并按照创建时间倒叙排列（hql中带参数的查询）
@Test ???public void testFindPorjectByCondition(){ ???????//获取hibernate session ???????Session session = HibernateUtils.getSession(); ???????String addr = "龙"; ???????//定义hql语句 ???????String hql = ?"from com.deng.hibernate.bean.Project project " + ??????????????// " where project.address like ? " + ??基于问号的参数 ???????????????" where project.address like :myaddr " +//基于命名的参数,冒号是命名参数的语法开始 ???????????????" order by project.createTime desc"; // "select * from project"; ???????//创建一个查询对象Query ???????Query query = session.createQuery(hql); ???????//设置参数,需要注意，问号参数的位置从0开始 ???????query.setString("myaddr","%"+addr+"%"); ????// ??query.setString(0,"%"+addr+"%"); ???????//调用query的相关方法来执行相关的动作 ???????List<Project> list = query.list(); ???????System.out.println(list); ???????session.close(); ???}需求3：查询出公司名包含【新希望】的公司下的所有的项目。
项目和 公司的关系是多对一，在Project对象中有
?@Basic ???@ManyToOne ???@JoinColumn(name = "company_id") ???public Company getCompany() { ???????return company; ???}此时的做法：
@Test ???public void testFindProjectByCompanyName(){ ???????Session session = HibernateUtils.getSession(); ???????String hql = "from com.deng.hibernate.bean.Project p where " + ???????????????" p.company.companyName like :cname "; ???????Query query = session.createQuery(hql); ???????query.setString("cname","%新希望%"); ???????List<Project> list = query.list(); ???????System.out.println(list); ???????session.close(); ???}需求4. 查询出所有的项目，根据创建时间倒叙排列，要求是第三页的数据（每页3行）
@Test ???public void testFindProjectByPage(){ ???????Session session = HibernateUtils.getSession(); ???????String hql = "from com.deng.hibernate.bean.Project p order by p.createTime desc"; ???????Query query = session.createQuery(hql); ???????//设置结果集的起始索引，也就是从多少行开始取 ???????query.setFirstResult(6); ???????//设置最多获取多少条数据 ???????query.setMaxResults(3); ???????List<Project> list = query.list(); ???????System.out.println(list); ???????session.close(); ???}需求5. 获取总共有多少个项目
@Test ???public void testCountProject(){ ???????Session session = HibernateUtils.getSession(); ???????String hql = "select count(1) from com.deng.hibernate.bean.Project p "; ???????Query query = session.createQuery(hql); ???????//uniqueResult 返回唯一的结果 ???????Long count = (Long)query.uniqueResult(); ???????System.out.println("----------->"+count); ???????session.close(); ???}需求6. 统计每个项目的可租面积和产权面积的综合
//查询出所有资源的可租面积总和，产权面积总和 ???@Test ???public void testSumResource(){ ???????Session session = HibernateUtils.getSession(); ???????String hql = "select res.project, sum(res.measureArea) as allArea,sum(res.canLeaseArea) as can from Resource res " + ???????????????" group by res.project"; ???????Query query = session.createQuery(hql); ???????//有多行数据时 ???????List<Object[]> list = query.list(); ???????//只有一行数据// ???????Object[] obj = (Object[])query.uniqueResult();// ???????System.out.println(obj[0]);// ???????System.out.println(obj[1]); ???????session.close(); ???}Hibernate:基于HQL实现数据查询
原文地址：http://www.cnblogs.com/dengcl/p/7609858.html