Hibernate查询(Query Language)-白红宇

Hibernate查询(Query Language)

阅读量：5846 次

发布时间：2019-06-18

本文共 11224 字，大约阅读时间需要 37 分钟。

查询方式:

1. NativeSQL (Mysql, oracle, sql server等)>HQL>EJBQL

2. QL应该与导航关系结合, 共同为查询提供服务

category->topic: one to more:

package com.bjsxt.hibernate;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;@Entitypublic class Category {	private int id;	private String name;	@Id	@GeneratedValue	public int getId() {		return id;	}	public void setId(int id) {		this.id = id;	}	public String getName() {		return name;	}	public void setName(String name) {		this.name = name;	}}

Topic->msg: one to more:

package com.bjsxt.hibernate;import java.util.Date;import javax.persistence.Entity;import javax.persistence.FetchType;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.ManyToOne;@Entitypublic class Topic {	private int id;	private String title;	private Category category;	//private Category category2;		private Date createDate;		public Date getCreateDate() {		return createDate;	}	public void setCreateDate(Date createDate) {		this.createDate = createDate;	}	@ManyToOne(fetch=FetchType.LAZY)	public Category getCategory() {		return category;	}	public void setCategory(Category category) {		this.category = category;	}	@Id	@GeneratedValue	public int getId() {		return id;	}	public void setId(int id) {		this.id = id;	}	public String getTitle() {		return title;	}	public void setTitle(String title) {		this.title = title;	}	}

msg.java;

package com.bjsxt.hibernate;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.ManyToOne;@Entitypublic class Msg {	private int id;	private String cont;	private Topic topic;	@ManyToOne	public Topic getTopic() {		return topic;	}	public void setTopic(Topic topic) {		this.topic = topic;	}	@Id	@GeneratedValue	public int getId() {		return id;	}	public void setId(int id) {		this.id = id;	}		public String getCont() {		return cont;	}	public void setCont(String cont) {		this.cont = cont;	}	}

hibernate.cfg.xml:


     
         
                       
       
        com.mysql.jdbc.Driver
               
       
        jdbc:mysql://localhost/hibernate
               
       
        root
               
       
        linda0213
               
       
        org.hibernate.dialect.MySQLDialect
              
               
               
       
        1
                       
               
       
        thread
               
               
       
        org.hibernate.cache.NoCacheProvider
               
               
       
        true
               
       
        true

test文件:

package com.bjsxt.hibernate;import java.util.Date;import java.util.List;import org.hibernate.Query; import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.cfg.AnnotationConfiguration;import org.hibernate.tool.hbm2ddl.SchemaExport;import org.junit.AfterClass;import org.junit.BeforeClass;import org.junit.Test;public class HibernateQLTest {	private static SessionFactory sf;		@BeforeClass	public static void beforeClass() {		sf = new AnnotationConfiguration().configure().buildSessionFactory();	}	@AfterClass	public static void afterClass() {		sf.close();	}		@Test	public void testSchemaExport() {		new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);	}		@Test	public void testSave() {		Session session = sf.openSession();		session.beginTransaction();				for(int i=0; i<10; i++) {			Category c = new Category();			c.setName("c" + i);			session.save(c);		}				for(int i=0; i<10; i++) {			Category c = new Category();			c.setId(1);			Topic t = new Topic();			t.setCategory(c);			t.setTitle("t" + i);			t.setCreateDate(new Date());			session.save(t);					}				for(int i=0; i<10; i++) {						Topic t = new Topic();			t.setId(1);			Msg m = new Msg();			m.setCont("m" + i);			m.setTopic(t);			session.save(m);					}										session.getTransaction().commit();		session.close();	}	@Test	public void testHQL_01() {		Session session = sf.openSession();		session.beginTransaction();		Query q = session.createQuery("from Category");		List
     
       categories = (List
      
       )q.list();		for(Category c : categories) {			System.out.println(c.getId()+" "+c.getName());		}		session.getTransaction().commit();		session.close();			}		@Test	public void testHQL_02() {		Session session = sf.openSession();		session.beginTransaction();		Query q = session.createQuery("from Category c where c.name > 'c5'");		List
       
         categories = (List
        
         )q.list();		for(Category c : categories) {			System.out.println(c.getName());		}		session.getTransaction().commit();		session.close();			}		@Test	public void testHQL_03() {		Session session = sf.openSession();		session.beginTransaction();		Query q = session.createQuery("from Category c order by c.name desc");		List
         
           categories = (List
          
           )q.list(); for(Category c : categories) { System.out.println(c.getName()); } session.getTransaction().commit(); session.close(); } @Test public void testHQL_04() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("select distinct c from Category c order by c.name desc"); List
           
             categories = (List
            
             )q.list(); for(Category c : categories) { System.out.println(c.getName()); } session.getTransaction().commit(); session.close(); } @Test public void testHQL_05() { Session session = sf.openSession(); session.beginTransaction(); /*Query q = session.createQuery("from Category c where c.id > :min and c.id < :max"); //q.setParameter("min", 2); //q.setParameter("max", 8); q.setInteger("min", 2); q.setInteger("max", 8);*/ Query q = session.createQuery("from Category c where c.id > :min and c.id < :max") .setInteger("min", 2) .setInteger("max", 8); List
             
               categories = (List
              
               )q.list(); for(Category c : categories) { System.out.println(c.getId() + "-" + c.getName()); } session.getTransaction().commit(); session.close(); } @Test public void testHQL_06() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("from Category c where c.id > ? and c.id < ?"); q.setParameter(0, 2) .setParameter(1, 8);// q.setParameter(1, 8); List
               
                 categories = (List
                
                 )q.list(); for(Category c : categories) { System.out.println(c.getId() + "-" + c.getName()); } session.getTransaction().commit(); session.close(); } //分页 @Test public void testHQL_07() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("from Category c order by c.name desc"); q.setMaxResults(4); q.setFirstResult(2); List
                 
                   categories = (List
                  
                   )q.list(); for(Category c : categories) { System.out.println(c.getId() + "-" + c.getName()); } session.getTransaction().commit(); session.close(); } @Test public void testHQL_08() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("select c.id, c.name from Category c order by c.name desc"); List
                   
                     categories = (List
                    
                     )q.list(); for(Object[] o : categories) { System.out.println(o[0] + "-" + o[1]); } session.getTransaction().commit(); session.close(); } //Topic 设定fetch type为lazy后, 将不会产生第二条sql语句. @Test public void testHQL_09() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("from Topic t where t.category.id = 1"); List
                     
                       topics = (List
                      
                       )q.list(); for(Topic t : topics) { System.out.println(t.getTitle()); //System.out.println(t.getCategory().getName()); } session.getTransaction().commit(); session.close(); } //�趨fetch type Ϊlazy�?����еڶ���sql��� @Test public void testHQL_10() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("from Topic t where t.category.id = 1"); List
                       
                         topics = (List
                        
                         )q.list(); for(Topic t : topics) { System.out.println(t.getTitle()); } session.getTransaction().commit(); session.close(); } @Test public void testHQL_11() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("from Msg m where m.topic.category.id = 1"); for(Object o : q.list()) { Msg m = (Msg)o; System.out.println(m.getCont()); } session.getTransaction().commit(); session.close(); } //了解即可 //VO Value Object //DTO data transfer object @Test public void testHQL_12() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("select new com.bjsxt.hibernate.MsgInfo(m.id, m.cont, m.topic.title, m.topic.category.name) from Msg"); for(Object o : q.list()) { MsgInfo m = (MsgInfo)o; System.out.println(m.getCont()); } session.getTransaction().commit(); session.close(); } //动手测试left right join //为什么不能直接写Category名, 而必须写t.category //因为有可能存在多个成员变量(同一个类), 需要指明用哪一个成员变量的连接条件做连接 @Test public void testHQL_13() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("select t.title, c.name from Topic t join t.category c "); //join Category c for(Object o : q.list()) { Object[] m = (Object[])o; System.out.println(m[0] + "-" + m[1]); } session.getTransaction().commit(); session.close(); } //学习使用uniqueResult @Test public void testHQL_14() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("from Msg m where m = :MsgToSearch "); //不重要 Msg m = new Msg(); m.setId(1); q.setParameter("MsgToSearch", m); Msg mResult = (Msg)q.uniqueResult(); System.out.println(mResult.getCont()); session.getTransaction().commit(); session.close(); } @Test public void testHQL_15() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("select count(*) from Msg m"); long count = (Long)q.uniqueResult(); System.out.println(count); session.getTransaction().commit(); session.close(); } @Test public void testHQL_16() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("select max(m.id), min(m.id), avg(m.id), sum(m.id) from Msg m"); Object[] o = (Object[])q.uniqueResult(); System.out.println(o[0] + "-" + o[1] + "-" + o[2] + "-" + o[3]); session.getTransaction().commit(); session.close(); } @Test public void testHQL_17() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("from Msg m where m.id between 3 and 5"); for(Object o : q.list()) { Msg m = (Msg)o; System.out.println(m.getId() + "-" + m.getCont()); } session.getTransaction().commit(); session.close(); } @Test public void testHQL_18() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("from Msg m where m.id in (3,4, 5)"); for(Object o : q.list()) { Msg m = (Msg)o; System.out.println(m.getId() + "-" + m.getCont()); } session.getTransaction().commit(); session.close(); } //is null �� is not null @Test public void testHQL_19() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("from Msg m where m.cont is not null"); for(Object o : q.list()) { Msg m = (Msg)o; System.out.println(m.getId() + "-" + m.getCont()); } session.getTransaction().commit(); session.close(); } public static void main(String[] args) { beforeClass(); }}