HQL基本语法

实体类：

package com.it.domain;

public class Customer {
	
	
	private Long cust_id;
	
	private String cust_name;
	private String cust_source;
	private String cust_industry;
	private String cust_level;
	private String cust_linkman;
	private String cust_phone;
	private String cust_mobile;
	public Long getCust_id() {
		return cust_id;
	}
	public void setCust_id(Long cust_id) {
		this.cust_id = cust_id;
	}
	public String getCust_name() {
		return cust_name;
	}
	public void setCust_name(String cust_name) {
		this.cust_name = cust_name;
	}
	public String getCust_source() {
		return cust_source;
	}
	public void setCust_source(String cust_source) {
		this.cust_source = cust_source;
	}
	public String getCust_industry() {
		return cust_industry;
	}
	public void setCust_industry(String cust_industry) {
		this.cust_industry = cust_industry;
	}
	public String getCust_level() {
		return cust_level;
	}
	public void setCust_level(String cust_level) {
		this.cust_level = cust_level;
	}
	public String getCust_linkman() {
		return cust_linkman;
	}
	public void setCust_linkman(String cust_linkman) {
		this.cust_linkman = cust_linkman;
	}
	public String getCust_phone() {
		return cust_phone;
	}
	public void setCust_phone(String cust_phone) {
		this.cust_phone = cust_phone;
	}
	public String getCust_mobile() {
		return cust_mobile;
	}
	public void setCust_mobile(String cust_mobile) {
		this.cust_mobile = cust_mobile;
	}
	@Override
	public String toString() {
		return "Customer [cust_id=" + cust_id + ", cust_name=" + cust_name + "]";
	}
	
	
	

}

1.查询所有信息

        @Test
	public void func1() {
		Configuration configure = new Configuration().configure();
		SessionFactory sessionFactory = configure.buildSessionFactory();
		Session session = sessionFactory.openSession();
		Transaction transaction = session.beginTransaction();
		
		String hql1 = " from com.it.domain.Customer ";//完整写法
		String hql2 = " from Customer ";//简单写法
		
		Query createQuery = session.createQuery(hql1);
		List list = createQuery.list();
		System.out.println(list);
		
		transaction.commit();
		session.close();
		
		
	}

2. 排序

        @Test
	public void func2() {
		Configuration configure = new Configuration().configure();
		SessionFactory sessionFactory = configure.buildSessionFactory();
		Session session = sessionFactory.openSession();
		Transaction transaction = session.beginTransaction();
		
		String hql1 = " from com.it.domain.Customer order by cust_id asc";//完整写法
		String hql2 = " from Customer order by cust_id desc";//简单写法
		
		Query createQuery1 = session.createQuery(hql1);
		List list1 = createQuery1.list();
		System.out.println(list1);
		
		Query createQuery2 = session.createQuery(hql2);
		List list2 = createQuery2.list();
		System.out.println(list2);
		
		transaction.commit();
		session.close();
		
		
	}

 

正序：

 反序：

 

 3.条件查询

        @Test
	public void func3() {
		Configuration configure = new Configuration().configure();
		SessionFactory sessionFactory = configure.buildSessionFactory();
		Session session = sessionFactory.openSession();
		Transaction transaction = session.beginTransaction();
		
		String hql1 = " from com.it.domain.Customer where cust_id=?";//完整写法
		String hql2 = " from Customer where cust_id=:cust_id";//简单写法
		
		Query createQuery1 = session.createQuery(hql1);
		createQuery1.setParameter(0,1l);//因为cust_id是Long 所以是 1l ， 2l
		List list1 = createQuery1.list();
		System.out.println(list1);
		
		Query createQuery2 = session.createQuery(hql2);
		createQuery2.setParameter("cust_id",2l);
		List list2 = createQuery2.list();
		System.out.println(list2);
		
		transaction.commit();
		session.close();
		
		
	}

 

 

 4.分页查询

        @Test
	public void func4() {
		Configuration configure = new Configuration().configure();
		SessionFactory sessionFactory = configure.buildSessionFactory();
		Session session = sessionFactory.openSession();
		Transaction transaction = session.beginTransaction();
		
		String hql1 = " from com.it.domain.Customer ";//完整写法
		String hql2 = " from Customer ";//简单写法
		
		Query createQuery1 = session.createQuery(hql1);
		//limit ? ? 
		//第一个参数=（当前页-1）*每页显示条数
		//第二个参数=每页显示条数
		//查询第一页，查询两条数据
		createQuery1.setFirstResult(0);
		createQuery1.setMaxResults(1);
		
		List list1 = createQuery1.list();
		System.out.println(list1);
		
		Query createQuery2 = session.createQuery(hql2);
		//查询第二页，显示一条数据
		createQuery2.setFirstResult(1);
		createQuery2.setMaxResults(1);
		
		List list2 = createQuery2.list();
		System.out.println(list2);
		
		
		Query createQuery3 = session.createQuery(hql2);
		//查询第一页，显示二条数据
		createQuery3.setFirstResult(0);
		createQuery3.setMaxResults(2);
		
		List list3 = createQuery3.list();
		System.out.println(list3);
		transaction.commit();
		session.close();
		
	}

 

 

 5.统计查询

        @Test
	public void func5() {
		Configuration configure = new Configuration().configure();
		SessionFactory sessionFactory = configure.buildSessionFactory();
		Session session = sessionFactory.openSession();
		Transaction transaction = session.beginTransaction();
		
		String hql1 = "select count(*) from com.it.domain.Customer ";//完整写法
		String hql2 = "select sum(*) from com.it.domain.Customer ";//完整写法
		String hql3 = "select avg(*) from com.it.domain.Customer ";//完整写法
		String hql4 = "select max(*) from com.it.domain.Customer ";//完整写法
		String hql5 = "select min(*) from com.it.domain.Customer ";//完整写法
		
		//以hql1为例
		Query createQuery = session.createQuery(hql1);
		Number number = (Number) createQuery.uniqueResult();
		System.out.println(number);
		
		transaction.commit();
		session.close();
		
	}

 

 6.投影查询（也就是查询一部分）hql3需要实现Customer有参的构造方法

        public Customer() {
	}
	public Customer(Long cust_id, String cust_name) {
		super();
		this.cust_id = cust_id;
		this.cust_name = cust_name;
	}

 

        @Test
	public void func6() {
		Configuration configure = new Configuration().configure();
		SessionFactory sessionFactory = configure.buildSessionFactory();
		Session session = sessionFactory.openSession();
		Transaction transaction = session.beginTransaction();
		
		String hql1 = "select cust_name from com.it.domain.Customer ";
		String hql2 = "select cust_id,cust_name from com.it.domain.Customer ";
		String hql3 = "select new Customer(cust_id,cust_name) from com.it.domain.Customer ";
		
		Query createQuery1 = session.createQuery(hql1);
		List list1 = createQuery1.list();
		System.out.println(list1);
		
		Query createQuery2 = session.createQuery(hql2);
		List list2 = createQuery2.list();
		System.out.println(list2);
		
		Query createQuery3 = session.createQuery(hql3);
		List list3 = createQuery3.list();
		System.out.println(list3);
		
		transaction.commit();
		session.close();
		
	}