Two previous retrieval methods

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The navigation object graph must set the association mapping relationship
OID retrieval method must retrieve the data corresponding to this object through the primary key

Three new search methods

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SQL is generally used when HQL cannot be used

HQL

Introduction

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HQL is an object-oriented query language, and the fields are all related to the class.
Execute query statements through the Query interface

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Asterisks cannot appear in HQL statements.
HQL keys are not case-sensitive, but others are case-sensitive

SQL:	select * from user;
HQL:	from User

select A from B basics

package com.hibernate.ui;

import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.hibernate.Session;
import org.hibernate.Transaction;
import org.hibernate.query.Query;

import com.hibernate.entity.Order;
import com.hibernate.entity.User;
import com.hibernate.util.HibernateUtil;

public class Test {
    
    

	public static void main(String[] args) {
    
    
//		saveUserAndOrder();		
//		addOrder();		
//		getUserAndOrders();		
//		deleteUser();
		
		
		testHQL();
		
		HibernateUtil.closeSessionFactory();
	}
	
	
	//HQL检索方式
	private static void testHQL() {
    
    
		Session session = HibernateUtil.openSession();
		//检索表中所有记录的所有字段
		//User不是关键字，是对象类型，所以区分大小写
//		String hql = "from User";
//		String hql = "select u from User u";//与上一句等价,这是起别名
//		import org.hibernate.query.Query;注意引用的包别错了
//		List<User> userList = query.list();
//		System.out.println(userList);
		
		
		
//		//查询某个字段的值
//		String hql = "select u.id from User u";
//		Query query = session.createQuery(hql);
//		//当查询结果中包含多条记录时，使用list方法执行HQL查询
//		List<User> userList = query.list();
//		System.out.println(userList);		
//		//当检索所有记录的某个字段时，结果中List集合元素的类型是该字段类型
//		List<Integer> userIds = query.list();
//		System.out.println(userIds);
		
		
		
		
		
		
		
//		//查询多个字段
//		String hql = "select u.userName, u.password from User u";
//		Query query = session.createQuery(hql);	
//		//当检索多个字段时，结果中List集合元素的类型是Object[]
//		List<Object[]> users = query.list();
//		for(Object[] o : users) {
    
    
//			System.out.println("用户名：" + o[0]);
//			System.out.println("密码：" + o[1]);
//		}
		
		
		//查询多个字段，推荐这种方式
//		String hql = "select u.userName, u.password from User u";
		//在HQL中可以直接调用构造方法(与上一句等价)
		//有条件：在User类里面加上带参数的构造方法
		//定义了带参数的构造方法同时也要定义无参构造方法
		String hql = "select new User(u.userName, u.password) from User u";
		Query query = session.createQuery(hql);	
		List<User> userList = query.list();
		System.out.println(userList);	
	}
}

where clause

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//		//where
//		String hql = "from User where userName = '张三'";
//		Query query = session.createQuery(hql);
//		List<User> users = query.list();
//		System.out.println(users);
		
		
//			//模糊查询
//		String hql = "from User as u where u.userName like '张%'";//起别名使用as关键字，该关键字可以省略
//		String hql = "from User where userName='Tom'";
//		Query query = session.createQuery(hql);
//		List<User> users = query.list();
//		System.out.println(users);

HQL alias query

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HQL polymorphic query

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Where there is inheritance mapping, the code is up to you.

		//多态查询
		//SQL注入代码
//		String name = "1 or 1 = 1";
//		String password = "1 or 1 = 1";
//		String hql = "from User where userName = " + name + " and password=" + password;
		
		//查询结果中只有一条记录，直接返回单个对象
//		User user = (User) query.uniqueResult();
//		System.out.println(user);

HQL to retrieve a single object

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		//多态查询
		//SQL注入代码
//		String name = "1 or 1 = 1";
//		String password = "1 or 1 = 1";
//		String hql = "from User where userName = " + name + " and password=" + password;
		
		//查询结果中只有一条记录，直接返回单个对象
//		User user = (User) query.uniqueResult();
//		System.out.println(user);

HQL grouping and sorting

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		//排序order by,默认升序排列
//		String hql = "from User u order by u.id desc";
//		Query query = session.createQuery(hql);
//		List<User> users = query.list();
//		System.out.println(users);
		
		
		
		
		
//		//group by 分组
//		String hql = "select u.userName, count(u) from User u group by u.userName having u.userName != 'Tom'";
//		Query query = session.createQuery(hql);
//		List<Object[]> users = query.list();
//		for(Object[] o : users) {
    
    
//			System.out.println("用户名：" + o[0]);
//			System.out.println("个数：" + o[1]);
//		}

HQL parameter binding

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		//HQL传参方式?占位符
//		String hql = "from User where userName = ? and password = ?";
//		Query query = session.createQuery(hql);
//		query.setParameter(0, "张三");
//		query.setParameter(1, "111");
//		System.out.println(query.list());

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		//按照参数名称进行传参
		//把上面的问号换成冒号+属性 
//		String hql = "from User where userName = :username and password = :password";
//		Query query = session.createQuery(hql);
//		query.setParameter("username", "张三");
//		query.setParameter("password", "111");
//		System.out.println(query.list());

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//		//使用命名参数
//		//HQL语句中命名参数的名称同setProperties方法参数中传入的对象的属性名称要一致
//		String hql = "from User where userName = :userName and password = :password";
//		Query query = session.createQuery(hql);
//		User u = new User();
//		u.setUserName("张三");
//		u.setPassword("111");
//		query.setProperties(u);
//		System.out.println(query.list());
		
		
		
		
		
		
		//setProperties传入Map类型的对象
//		String hql = "from User where userName = :userName and password = :password";
//		Query query = session.createQuery(hql);
//		Map<String, Object> pro = new HashMap<>();
//		pro.put("userName", "张三");
//		pro.put("password", "111");
//		query.setProperties(pro);//HQL语句中命名参数的名称同setProperties方法参数中传入的Map对象的key名称要一致
//		System.out.println(query.list());