HQL 简单使用二
摘要: HQL的简单使用2
1、 Category类
package com.edu.hpu;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
@Entity
public class Category {
pri
HQL的简单使用2
1、 Category类
package com.edu.hpu;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
@Entity
public 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;
}
}
2、 Msg类
package com.edu.hpu;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
@Entity
public class Msg {
private int id;
private String cont;
private 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;
}
@ManyToOne
@JoinColumn(name="topic_ID")
public Topic getTopic() {
return topic;
}
public void setTopic(Topic topic) {
this.topic = topic;
}
}
3、 Topic类
package com.edu.hpu;
import java.util.Date;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
@Entity
public class Topic {
private int id;
private String title;
private Date date;
private Category category;
private Set<Msg> msgs = new HashSet<Msg>();
@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;
}
public Date getDate() {
return date;
}
public void setDate(Date date) {
this.date = date;
}
@ManyToOne(fetch=FetchType.LAZY)
@JoinColumn(name="category_ID")
public Category getCategory() {
return category;
}
public void setCategory(Category category) {
this.category = category;
}
@OneToMany(mappedBy="topic")
public Set<Msg> getMsgs() {
return msgs;
}
public void setMsgs(Set<Msg> msgs) {
this.msgs = msgs;
}
}
4、 测试类
package com.edu.hpu;
import java.util.Date;
import java.util.List;
import org.hibernate.Query;
import org.hibernate.SQLQuery;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;
public class TestClass {
private static SessionFactory sf = null;
@BeforeClass
public static void beforeClass() {
Configuration conf = new Configuration().configure();
ServiceRegistry sr = new ServiceRegistryBuilder().applySettings(conf.getProperties()).buildServiceRegistry();
sf = conf.buildSessionFactory(sr);
}
@Test
public void testExport() {
new SchemaExport(new Configuration().configure()).create(true ,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.setTitle("t" + i);
t.setCategory(c);
session.save(t);
}
for(int i = 0; i < 10; i++) {
Topic t = new Topic();
t.setId(1);
Msg m = new Msg();
m.setTopic(t);
m.setCont("m" + i);
session.save(m);
}
session.getTransaction().commit();
session.close();
}
@Test
public void testHQL_19() {
Session s = sf.getCurrentSession();
s.beginTransaction();
Query q = s.createQuery("from Topic t where t.msgs is empty");
List<Topic> ts = q.list();
for(Topic t : ts) {
System.out.println(t.getTitle());
}
s.getTransaction().commit();
}
//like % 代表零个或多个
@Test
public void testHQL_20() {
Session s = sf.getCurrentSession();
s.beginTransaction();
Query q = s.createQuery("from Topic t where t.title like '%5'");
List<Topic> ts = q.list();
for(Topic t : ts) {
System.out.println(t.getTitle());
}
s.getTransaction().commit();
}
//like % 代表一个或多个
@Test
public void testHQL_21() {
Session s = sf.getCurrentSession();
s.beginTransaction();
Query q = s.createQuery("from Topic t where t.title like '_5'");
List<Topic> ts = q.list();
for(Topic t : ts) {
System.out.println(t.getTitle());
}
s.getTransaction().commit();
}
@Test
public void testHQL_22() {
Session s = sf.getCurrentSession();
s.beginTransaction();
Query q = s.createQuery("select current_time , current_date , current_timestamp , t.id from Topic t");
List<Object[]> objs = (List<Object[]>)q.list();
for(Object[] obj : objs) {
System.out.println(obj[0] + " " + obj[1] + " " + obj[2] + " " + obj[3]);
}
s.getTransaction().commit();
}
@Test
public void testHQL_23() {
Session s = sf.getCurrentSession();
s.beginTransaction();
Query q = s.createQuery("from Topic t where t.date < :now");
q.setParameter("now", new Date());
List<Topic> ts = (List<Topic>)q.list();
for(Topic t : ts) {
System.out.println(t.getId() + " " + t.getTitle());
}
s.getTransaction().commit();
}
@Test
public void testHQL_24() {
Session s = sf.getCurrentSession();
s.beginTransaction();
Query q = s.createQuery("select t.title , count(*) from Topic t group by t.title");
List<Object[]> objs = (List<Object[]>)q.list();
for(Object[] obj : objs) {
System.out.println(obj[0] + " " + obj[1]);
}
s.getTransaction().commit();
}
@Test
public void testHQL_25() {
Session s = sf.getCurrentSession();
s.beginTransaction();
Query q = s.createQuery("select t.title , count(*) from Topic t group by t.title having count(*) >= 1");
List<Object[]> objs = (List<Object[]>)q.list();
for(Object[] obj : objs) {
System.out.println(obj[0] + " " + obj[1]);
}
s.getTransaction().commit();
}
@Test
public void testHQL_26() {
Session s = sf.getCurrentSession();
s.beginTransaction();
Query q = s.createQuery("from Topic t where t.id < (select avg(t.id) from Topic t)");
List<Topic> ts = q.list();
for(Topic t : ts) {
System.out.println(t.getId() + " " + t.getTitle());
}
s.getTransaction().commit();
}
@Test
public void testHQL_27() {
Session s = sf.getCurrentSession();
s.beginTransaction();
Query q = s.createQuery("from Topic t where t.id < ALL (select t.id from Topic t where mod(t.id , 2) = 0)");
List<Topic> ts = (List<Topic>)q.list();
for(Topic t : ts) {
System.out.println(t.getId() + " " + t.getTitle());
}
s.getTransaction().commit();
}
//exists 可以用in来实现，如果exists 执行效率高
@Test
public void testHQL_28() {
Session s = sf.getCurrentSession();
s.beginTransaction();
//Query q = s.createQuery("from Topic t where not exists (select m.id from Msg m where m.topic.id = t.id)");
Query q = s.createQuery("from Topic t where t.id in (select t.id from Msg m where m.topic.id != t.id)");
List<Topic> ts = (List<Topic>)q.list();
for(Topic t : ts) {
System.out.println(t.getId() + " " + t.getTitle());
}
s.getTransaction().commit();
}
@Test
public void testHQL_29() {
Session s = sf.getCurrentSession();
s.beginTransaction();
Query q = s.createQuery("update Topic t set t.title = upper(t.title)");
q.executeUpdate();
q = s.createQuery("from Topic");
List<Topic> ts = (List<Topic>)q.list();
for(Topic t : ts) {
System.out.println(t.getId() + " " + t.getTitle());
}
s.createQuery("update Topic t set t.title = lower(t.title)" ).executeUpdate();
s.getTransaction().commit();
}
@Test
public void testHQL_30() {
Session s = sf.getCurrentSession();
s.beginTransaction();
SQLQuery sq = s.createSQLQuery("select * from category limit 2,4").addEntity(Category.class);
List<Category> cs = (List<Category>)sq.list();
for(Category c : cs) {
System.out.println(c.getId() + " " + c.getName());
}
s.getTransaction().commit();
}
@AfterClass
public static void afterClass() {
sf.close();
}
}
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