HQL基本语法

冷不防 2022-03-26 15:14 185阅读 0赞

![20190117165541752.png][]

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();
    		
    		
    	}

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNTY2Nzcy_size_16_color_FFFFFF_t_70][]

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：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNTY2Nzcy_size_16_color_FFFFFF_t_70 1][]

反序：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNTY2Nzcy_size_16_color_FFFFFF_t_70 2][]

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();
    		
    		
    	}

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNTY2Nzcy_size_16_color_FFFFFF_t_70 3][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNTY2Nzcy_size_16_color_FFFFFF_t_70 4][]

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();
    		
    	}

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNTY2Nzcy_size_16_color_FFFFFF_t_70 5][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNTY2Nzcy_size_16_color_FFFFFF_t_70 6][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNTY2Nzcy_size_16_color_FFFFFF_t_70 7][]

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();
    		
    	}

![20190117172125953.png][]

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();
    		
    	}

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNTY2Nzcy_size_16_color_FFFFFF_t_70 8][]

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[20190117172125953.png]: /images/20220326/aaefd097d53242b4a4001219ae7b3020.png
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