hibernate使用Query进行查询
hibernate使用Query进行查询
本文主要探讨hibernate的简单查询，主要是使用Query进行的查询。
1.首先看下annotation的API中关于查询的描述
2.3.&映射查询
2.3.1.&映射EJBQL/HQL查询
使用注解还可以映射EJBQL/HQL查询.&@NamedQuery&和@NamedQueries是可使用在类和包上的注解. 但是它们的定义在session
factory/entity manager factory范围中是都可见的. 命名式查询通过它的名字和实际的查询字符串来定义.
javax.persistence.NamedQueries(
@javax.persistence.NamedQuery(name=&plane.getAll&, query=&select p from Plane p&)
package org.hibernate.test.annotations.
@NamedQuery(name=&night.moreRecentThan&, query=&select n from Night n where n.date &= :date&)
public class Night {
public class MyDao {
doStuff() {
Query q = s.getNamedQuery(&night.moreRecentThan&);
q.setDate( &date&, aMonthAgo );
List results = q.list();
还可以通过定义&QueryHint&数组的hints&属性为查询提供一些hint信息.
下面是目前可以使用的一些Hibernate hint：
表&2.2.&Query hints
description
org.hibernate.cacheable
查询是否与二级缓存交互(默认值为false)
org.hibernate.cacheRegion
设置缓存区名称 (默认为otherwise)
org.hibernate.timeout
查询超时设定
org.hibernate.fetchSize
所获取的结果集(resultset)大小
org.hibernate.flushMode
本次查询所用的刷新模式
org.hibernate.cacheMode
本次查询所用的缓存模式
org.hibernate.readOnly
是否将本次查询所加载的实体设为只读(默认为false)
将查询注释添加入所生成的SQL
2.3.2.&映射本地化查询
你还可以映射本地化查询(也就是普通SQL查询). 不过这需要你使用@SqlResultSetMapping注解来描述SQL的resultset的结构 (如果你打算定义多个结果集映射，可是使用@SqlResultSetMappings).&@SqlResultSetMapping和@NamedQuery,&@SqlResultSetMapping一样,可以定义在类和包一级.
但是@SqlResultSetMapping的作用域为应用级. 下面我们会看到,@NamedNativeQuery&注解中&resultSetMapping参数值为@SqlResultSetMapping的名字.
结果集映射定义了通过本地化查询返回值和实体的映射. 该实体中的每一个字段都绑定到SQL结果集中的某个列上. 该实体的所有字段包括子类的所有字段以及 关联实体的外键列都必须在SQL查询中有对应的定义. 如果实体中的属性和SQL查询中的列名相同,这种情况下可以不进行定义字段映射.
@NamedNativeQuery(name=&night&area&, query=&select night.id nid, night.night_duration, &
+ & night.night_date, area.id aid, night.area_id, area.name &
+ &from Night night, Area area where night.area_id = area.id&, resultSetMapping=&joinMapping&)
@SqlResultSetMapping(name=&joinMapping&, entities={
@EntityResult(entityClass=org.hibernate.test.annotations.query.Night.class, fields = {
@FieldResult(name=&id&, column=&nid&),
@FieldResult(name=&duration&, column=&night_duration&),
@FieldResult(name=&date&, column=&night_date&),
@FieldResult(name=&area&, column=&area_id&),
discriminatorColumn=&disc&
@EntityResult(entityClass=org.hibernate.test.annotations.query.Area.class, fields = {
@FieldResult(name=&id&, column=&aid&),
@FieldResult(name=&name&, column=&name&)
在上面这个例子中,名为night&area的查询 和joinMapping结果集映射对应. 该映射返回两个实体,分别为Night&和Area,其中每个属性都和一个列关联,
列名通过查询获取.下面我们看一个隐式声明属性和列映射关系的例子.
@SqlResultSetMapping(name=&implicit&, entities=@EntityResult(entityClass=org.hibernate.test.annotations.query.SpaceShip.class))
@NamedNativeQuery(name=&implicitSample&, query=&select * from SpaceShip&, resultSetMapping=&implicit&)
public class SpaceShip {
public String getName() {
public void setName(String name) {
this.name =
@Column(name=&model_txt&)
public String getModel() {
public void setModel(String model) {
this.model =
public double getSpeed() {
public void setSpeed(double speed) {
this.speed =
在这个例子中,我们只需要定义结果集映射中的实体成员. 属性和列名之间的映射借助实体中包含映射信息来完成. 在这个例子中,model属性绑定到model_txt列.
如果和相关实体的关联设计到组合主键, 那么应该使用@FieldResult注解来定义每个外键列.&@FieldResult的名字由以下几部分组成：
定义这种关系的属性名字+&.&＋主键名或主键列或主键属性.
@SqlResultSetMapping(name=&compositekey&,
entities=@EntityResult(entityClass=org.hibernate.test.annotations.query.SpaceShip.class,
fields = {
@FieldResult(name=&name&, column = &name&),
@FieldResult(name=&model&, column = &model&),
@FieldResult(name=&speed&, column = &speed&),
@FieldResult(name=&captain.firstname&, column = &firstn&),
@FieldResult(name=&captain.lastname&, column = &lastn&),
@FieldResult(name=&dimensions.length&, column = &length&),
@FieldResult(name=&dimensions.width&, column = &width&)
columns = { @ColumnResult(name = &surface&),
@ColumnResult(name = &volume&) } )
@NamedNativeQuery(name=&compositekey&,
query=&select name, model, speed, lname as lastn, fname as firstn, length, width, length * width as surface from SpaceShip&,
resultSetMapping=&compositekey&)
public class SpaceShip {
public String getName() {
public void setName(String name) {
this.name =
@ManyToOne(fetch= FetchType.LAZY)
@JoinColumns( {
@JoinColumn(name=&fname&, referencedColumnName = &firstname&),
@JoinColumn(name=&lname&, referencedColumnName = &lastname&)
public Captain getCaptain() {
public void setCaptain(Captain captain) {
this.captain =
public String getModel() {
public void setModel(String model) {
this.model =
public double getSpeed() {
public void setSpeed(double speed) {
this.speed =
public Dimensions getDimensions() {
public void setDimensions(Dimensions dimensions) {
this.dimensions =
@IdClass(Identity.class)
public class Captain implements Serializable {
public String getFirstname() {
public void setFirstname(String firstname) {
this.firstname =
public String getLastname() {
public void setLastname(String lastname) {
this.lastname =
观察dimension属性你会发现Hibernate支持用&.&符号来表示嵌入式对象. EJB3实现不必支持这个特征,但是我们做到了:-)
如果查询返回的是单个实体,或者你打算使用系统默认的映射, 这种情况下可以不使用resultSetMapping&而是使用resultClass属性:
@NamedNativeQuery(name=&implicitSample&, query=&select * from SpaceShip&,
resultClass=SpaceShip.class)
public class SpaceShip {
某些本地查询返回的是scalar值,例如报表查询. 你可以通过@ColumnResult将其映射到&@SqlResultsetMapping上.
甚至还可以在同一个本地查询的结果中混合实体和scalar类型(不过这种情况比较少见).
@SqlResultSetMapping(name=&scalar&, columns=@ColumnResult(name=&dimension&))
@NamedNativeQuery(name=&scalar&, query=&select length*width as dimension from SpaceShip&, resultSetMapping=&scalar&)
本地查询中还有另外一个hint属性：&org.hibernate.callable. 这个属性的布尔变量值表明这个查询是否是一个存储过程.
2.再来看下xml的API中关于查询的描述
中详细讨论。
3.查询练习
新建3个类，Category、Topic和Msg，其中Category和Topic是1对多，Topic和Msg是1对多
另外还有1个查询辅助类MsgInfo，注意此类不适用注解
package com.baosight.
import javax.persistence.E
import javax.persistence.GeneratedV
import javax.persistence.Id;
public class Category {
@GeneratedValue
public String getId() {
public void setId(String id) {
public String getName() {
public void setName(String name) {
this.name =
package com.baosight.
import java.util.D
import java.util.L
import javax.persistence.E
import javax.persistence.GeneratedV
import javax.persistence.Id;
import javax.persistence.ManyToO
import javax.persistence.NamedQ
import javax.persistence.NamedQ
import javax.persistence.OneToM
@NamedQueries({ @NamedQuery(name = &topic.selectCertainTopic&, query = &from Topic t where t.id=:id&) })
public class Topic {
private Date createD
private List&Msg&
@ManyToOne
public Category getCategory() {
public void setCategory(Category category) {
this.category =
@GeneratedValue
public String getId() {
public void setId(String id) {
public String getTitle() {
public void setTitle(String title) {
this.title =
public Date getCreateDate() {
return createD
public void setCreateDate(Date createDate) {
this.createDate = createD
@OneToMany(mappedBy=&topic&)
public List&Msg& getMsgs() {
public void setMsgs(List&Msg& msgs) {
this.msgs =
package com.baosight.
import javax.persistence.E
import javax.persistence.GeneratedV
import javax.persistence.Id;
import javax.persistence.ManyToO
public class Msg {
@GeneratedValue
public String getId() {
public void setId(String id) {
public String getCont() {
public void setCont(String cont) {
this.cont =
@ManyToOne
public Topic getTopic() {
public void setTopic(Topic topic) {
this.topic =
package com.baosight.
public class MsgInfo {
private String topicN
private String categoryN
public MsgInfo(String id, String cont, String topicName, String categoryName) {
this.cont =
this.topicName = topicN
this.categoryName = categoryN
public String getId() {
public void setId(String id) {
public String getCont() {
public void setCont(String cont) {
this.cont =
public String getTopicName() {
return topicN
public void setTopicName(String topicName) {
this.topicName = topicN
public String getCategoryName() {
return categoryN
public void setCategoryName(String categoryName) {
this.categoryName = categoryN
hibernate.cfg.xml
&?xml version='1.0' encoding='utf-8'?&
&!DOCTYPE hibernate-configuration PUBLIC
&-//Hibernate/Hibernate Configuration DTD 3.0//EN&
&http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd&&
&hibernate-configuration&
&session-factory&
&!-- Database connection settings --&
&property name=&connection.driver_class&&oracle.jdbc.driver.OracleDriver&/property&
&property name=&connection.url&&jdbc:oracle:thin:@127.0.0.1:1521:orcl&/property&
&property name=&connection.username&&scott&/property&
&property name=&connection.password&&tiger&/property&
&!-- JDBC connection pool (use the built-in) --&
&!-- &property name=&connection.pool_size&&1&/property& --&
&!-- SQL dialect --&
&property name=&dialect&&org.hibernate.dialect.Oracle9iDialect&/property&
&!-- Enable Hibernate's automatic session context management --&
&property name=&current_session_context_class&&thread&/property&
&!-- Disable the second-level cache
&property name=&cache.provider_class&&org.hibernate.cache.NoCacheProvider&/property&
&!-- Echo all executed SQL to stdout --&
&property name=&show_sql&&true&/property&
&property name=&format_sql&&true&/property&
&!-- Drop and re-create the database schema on startup --&
&property name=&hbm2ddl.auto&&update&/property& --&
&mapping class=&com.baosight.model.Category&/&
&mapping class=&com.baosight.model.Topic&/&
&mapping class=&com.baosight.model.Msg&/&
&/session-factory&
&/hibernate-configuration&
JUnit测试类
package com.baosight.
import java.util.D
import java.util.L
import java.util.M
import org.hibernate.Q
import org.hibernate.SQLQ
import org.hibernate.S
import org.hibernate.SessionF
import org.hibernate.cfg.AnnotationC
import org.hibernate.tool.hbm2ddl.SchemaE
import org.junit.AfterC
import org.junit.BeforeC
import org.junit.T
public class OrMappingTest {
private static SessionFactory sessionF
@BeforeClass
public static void beforeClass() {
//new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);
sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();
@AfterClass
public static void afterClass() {
sessionFactory.close();
public void testSave() {
//插入数据
Session session = sessionFactory.getCurrentSession();
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.setCreateDate(new Date());
t.setCategory(c);
session.save(t);
for(int i=0;i&10;i++){
Topic t = new Topic();
t.setId(&11&);
Msg m = new Msg();
m.setCont(&m&+i);
m.setTopic(t);
session.save(m);
session.getTransaction().commit();
public void testHQL01() {
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
List&Category& list = (List&Category&)session.createQuery(&from Category&).list();
for(Category c : list) {
System.out.println(c.getName());
session.getTransaction().commit();
public void testHQL02() {
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
//条件查询
List&Category& list = (List&Category&)session.createQuery(&from Category c where c.name&'c5'&).list();
for(Category c : list) {
System.out.println(c.getName());
session.getTransaction().commit();
public void testHQL03() {
String sql = &&;
sql = &from Category c order by c.name desc&;
sql = &select distinct c from Category c order by c.name desc&;
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
List&Category& list = (List&Category&)session.createQuery(sql).list();
for(Category c : list) {
System.out.println(c.getName());
session.getTransaction().commit();
public void testHQL04() {
//传参查询
String sql = &&;
sql = &from Category c where c.id&:min and c.id&:max order by c.name desc&;
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Query q = session.createQuery(sql);
q.setParameter(&min&, &2&);
q.setParameter(&max&, &8&);
List&Category& list = (List&Category&)q.list();
for(Category c : list) {
System.out.println(c.getId()+&--&+c.getName());
session.getTransaction().commit();
public void testHQL05() {
//分页查询
String sql = &&;
sql = &from Category c order by c.name desc&;
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Query q = session.createQuery(sql);
q.setMaxResults(4);//每页条数
q.setFirstResult(2);//开始行号
List&Category& list = (List&Category&)q.list();
for(Category c : list) {
System.out.println(c.getId()+&--&+c.getName());
session.getTransaction().commit();
public void testHQL06() {
//查询字段
String sql = &&;
sql = &select c.id,c.name from Category c order by c.name desc&;
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Query q = session.createQuery(sql);
List&Object[]& list = (List&Object[]&)q.list();
for(Object[] c : list) {
System.out.println(c[0]+&--&+c[1]);
session.getTransaction().commit();
public void testHQL07() {
//关联查询
String sql = &&;
sql = &from Topic t where t.category.id=1&;
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Query q = session.createQuery(sql);
List&Topic& list = (List&Topic&)q.list();
for(Topic c : list) {
System.out.println(c.getId()+&--&+c.getTitle());
System.out.println(c.getCategory().getId()+&--&+c.getCategory().getName());
session.getTransaction().commit();
public void testHQL08() {
//多级关联查询
String sql = &&;
sql = &from Msg m where m.topic.category.id=1&;
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Query q = session.createQuery(sql);
List&Msg& list = (List&Msg&)q.list();
for(Msg c : list) {
System.out.println(c.getId()+&--&+c.getCont());
System.out.println(c.getTopic().getTitle()+&--&+c.getTopic().getCategory().getName());
session.getTransaction().commit();
public void testHQL09() {
//通过辅助类查询
String sql = &&;
sql = &select new com.baosight.model.MsgInfo(m.id,m.cont,m.topic.title,m.topic.category.name) from Msg m&;
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Query q = session.createQuery(sql);
List list = q.list();
for(Object c : list) {
MsgInfo m = (MsgInfo)c;
System.out.println(m.getId()+&--&+m.getCont());
System.out.println(m.getTopicName()+&--&+m.getCategoryName());
session.getTransaction().commit();
public void testHQL10() {
//连接查询个别字段
String sql = &&;
sql = &select m.cont,t.title from Msg m join m.topic t&;
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Query q = session.createQuery(sql);
List&Object[]& list = (List&Object[]&)q.list();
for(Object[] c : list) {
System.out.println(c[0]+&--&+c[1]);
session.getTransaction().commit();
public void testHQL11() {
//使用uniqueResult
String sql = &&;
sql = &from Msg m where m=:msgToSearch&;
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Query q = session.createQuery(sql);
Msg m = new Msg();
m.setId(&21&);
q.setParameter(&msgToSearch&, m);
Msg msg = (Msg) q.uniqueResult();
System.out.println(msg.getId()+&--&+msg.getCont());
session.getTransaction().commit();
public void testHQL12() {
//使用uniqueResult
String sql = &&;
sql = &select count(*) from Msg m&;
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Query q = session.createQuery(sql);
Long count = (Long) q.uniqueResult();
System.out.println(count);
session.getTransaction().commit();
public void testHQL13() {
//使用聚合函数
String sql = &&;
sql = &select max(m.id),min(m.id),avg(m.id),sum(m.id) from Msg m&;
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Query q = session.createQuery(sql);
Object[] o = (Object[]) q.uniqueResult();
System.out.println(o[0]+&--&+o[1]+&--&+o[2]+&--&+o[3]);
session.getTransaction().commit();
public void testHQL14() {
//between and
String sql = &&;
sql = &from Msg m where m.id between 21 and 24&;
sql = &from Msg m where m.id in(22,23,24)&;
sql = &from Msg m where m.topic is not null&;
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Query q = session.createQuery(sql);
List&Msg& list = (List&Msg&)q.list();
for(Msg c : list) {
System.out.println(c.getId()+&--&+c.getCont());
System.out.println(c.getTopic().getTitle()+&--&+c.getTopic().getCategory().getName());
session.getTransaction().commit();
public void testHQL15() {
//is empty
String sql = &&;
sql = &from Topic t where t.msgs is empty&;
sql = &from Topic t where t.title like '%5'&;
sql = &from Topic t where t.title like '_5'&;
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Query q = session.createQuery(sql);
List&Topic& list = (List&Topic&)q.list();
for(Topic c : list) {
System.out.println(c.getId()+&--&+c.getTitle());
System.out.println(c.getTopic().getTitle()+&--&+c.getTopic().getCategory().getName());
session.getTransaction().commit();
public void testHQL16() {
//字段函数
String sql = &&;
sql = &select lower(m.cont),upper(m.cont),trim(m.cont),concat(m.cont,'***'),length(m.cont) from Msg m&;
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Query q = session.createQuery(sql);
List&Object[]& list = (List&Object[]&)q.list();
for(Object[] c : list) {
System.out.println(c[0]+&--&+c[1]+&--&+c[2]+&--&+c[3]+&--&+c[4]);
session.getTransaction().commit();
public void testHQL17() {
//运算函数
String sql = &&;
sql = &select abs(m.id),sqrt(m.id),mod(m.id,2) from Msg m&;
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Query q = session.createQuery(sql);
List&Object[]& list = (List&Object[]&)q.list();
for(Object[] c : list) {
System.out.println(c[0]+&--&+c[1]+&--&+c[2]);
session.getTransaction().commit();
public void testHQL18() {
//日期函数
String sql = &&;
sql = &select current_date,sysdate,current_timestamp,m.id from Msg m&;
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Query q = session.createQuery(sql);
List&Object[]& list = (List&Object[]&)q.list();
for(Object[] c : list) {
System.out.println(c[0]+&--&+c[1]+&--&+c[2]+&--&+c[3]);
session.getTransaction().commit();
public void testHQL19() {
//日期参数
String sql = &&;
sql = &from Topic t where t.createDate&:date&;
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Query q = session.createQuery(sql);
q.setParameter(&date&, new Date());
List&Topic& list = (List&Topic&)q.list();
for(Topic c : list) {
System.out.println(c.getId()+&--&+c.getTitle());
System.out.println(c.getTopic().getTitle()+&--&+c.getTopic().getCategory().getName());
session.getTransaction().commit();
public void testHQL20() {
//分组查询
String sql = &&;
sql = &select t.title,count(*) from Topic t group by t.title&;
sql = &select t.title,count(*) from Topic t group by t.title having count(*)&1&;
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Query q = session.createQuery(sql);
List&Object[]& list = (List&Object[]&)q.list();
for(Object[] c : list) {
System.out.println(c[0]+&--&+c[1]);
session.getTransaction().commit();
public void testHQL21() {
//exists的使用
String sql = &&;
sql = &from Topic t where t.id&(select avg(t1.id) from Topic t1)&;
sql = &from Topic t where t.id& all(select t1.id from Topic t1 where mod(t1.id,2)=0)&;
sql = &from Topic t where not exists(select m.id from Msg m where m.topic.id=t.id)&;
sql = &from Topic t where exists(select m.id from Msg m where m.topic.id=t.id)&;
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Query q = session.createQuery(sql);
List&Topic& list = (List&Topic&)q.list();
for(Topic c : list) {
System.out.println(c.getId()+&--&+c.getTitle());
System.out.println(c.getTopic().getTitle()+&--&+c.getTopic().getCategory().getName());
session.getTransaction().commit();
public void testHQL22() {
String sql = &&;
sql = &update Topic t set t.title=upper(t.title)&;
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Query q = session.createQuery(sql);
q.executeUpdate();
q = session.createQuery(&from Topic&);
List&Topic& list = (List&Topic&)q.list();
for(Topic c : list) {
System.out.println(c.getId()+&--&+c.getTitle());
System.out.println(c.getTopic().getTitle()+&--&+c.getTopic().getCategory().getName());
session.createQuery(&update Topic t set t.title=lower(t.title)&).executeUpdate();
session.getTransaction().commit();
public void testHQL23() {
//NamedQuery
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Query q = session.getNamedQuery(&topic.selectCertainTopic&);
q.setParameter(&id&, &15&);
Topic t = (Topic) q.uniqueResult();
System.out.println(t.getId()+&--&+t.getTitle());
session.getTransaction().commit();
public void testHQL24() {
Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
SQLQuery q = session.createSQLQuery(&select * from category&).addEntity(Category.class);
List&Category& list = (List&Category&)q.list();
for(Category c : list) {
System.out.println(c.getId()+&--&+c.getName());
System.out.println(c.getTopic().getTitle()+&--&+c.getTopic().getCategory().getName());
session.getTransaction().commit();
public void testSchemaExport() {
new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);
public static void main(String[] args) {
beforeClass();
4.首先执行测试类的testSchemaExport进行建表
4.1注意Topic中的private List&Msg&是后来测试is empty时添加的，刚开始并没有
4.2执行测试类的testSave插入测试数据
5.首先进行简单查询
5.1执行testHQL01进行单表查询
通过List&Category& list = (List&Category&)session.createQuery(&from Category&).list();
查询出结果集并进行遍历
5.2执行testHQL02进行单表条件查询
List&Category& list = (List&Category&)session.createQuery(&from Category c where c.name&'c5'&).list();
5.3执行testHQL03进行单表查询排序和使用distinct
sql = &from Category c order by c.name desc&;
sql = &select distinct c from Category c order by c.name desc&;
5.4执行testHQL04进行单表查询传入查询参数
使用:xx定义传入参数，使用q.setParameter(&xx&, Obj);传入参数
sql = &from Category c where c.id&:min and c.id&:max order by c.name desc&;
q.setParameter(&min&, &2&);
q.setParameter(&max&, &8&);
5.5执行testHQL05进行单表分页查询
使用q.setMaxResults(xx);设置每页条数；使用q.setFirstResult(xx);设置开始行号
sql = &from Category c order by c.name desc&;
q.setMaxResults(4);//每页条数
q.setFirstResult(2);//开始行号
5.6执行testHQL06进行单表字段查询
注意此时查询的结果是Object[]组成的list
sql = &select c.id,c.name from Category c order by c.name desc&;
List&Object[]& list = (List&Object[]&)q.list();
6.进行关联查询
6.1多对一关联查询，使用testHQL07
查询语句为sql = &from Topic t where t.category.id=1&;这体现了hibernate对象查询的本质，直接通过对象进行关联查询
6.2使用testHQL08进行多级关联
sql = &from Msg m where m.topic.category.id=1&;
6.3使用辅助类进行查询，此查询和ibatis里面的查询辅助类相似
sql = &select new com.baosight.model.MsgInfo(m.id,m.cont,m.topic.title,m.topic.category.name) from Msg m&;
运行testHQL09
6.4进行连接查询，运行testHQL10
sql = &select m.cont,t.title from Msg m join m.topic t&;
注意使用m.topic就指明了二者之间的连接字段
6.5使用uniqueResult，运行testHQL11
查询结果只有1条记录时可以使用类似于Msg msg = (Msg) q.uniqueResult();进行查询
一般适用于通过id进行查询，或者是使用聚合函数查询出单条记录等
6.6使用count查询统计，运行testHQL12
sql = &select count(*) from Msg m&;
Long count = (Long) q.uniqueResult();
查询结果是Long
6.7使用聚合函数查询统计，运行testHQL13
sql = &select max(m.id),min(m.id),avg(m.id),sum(m.id) from Msg m&;
7.条件查询
7.1使用between and/in/is not &null查询，运行testHQL14
sql = &from Msg m where m.id between 21 and 24&;
sql = &from Msg m where m.id in(22,23,24)&;
sql = &from Msg m where m.topic is not null&;
7.2使用is empty/like查询，运行testHQL15
上面6.7中is null是在多的一方查询1，如果想要在1的一方查询多，需要在1中配置@OneToMany(mappedBy=&topic&)
public List&Msg& getMsgs() {
查询时可以使用sql = &from Topic t where t.msgs is empty&;
sql = &from Topic t where t.title like '%5'&;
sql = &from Topic t where t.title like '_5'&;
8.使用常用函数进行查询
8.1使用字符串函数查询，运行testHQL16
sql = &select lower(m.cont),upper(m.cont),trim(m.cont),concat(m.cont,'***'),length(m.cont) from Msg m&;
8.2使用数学运算函数查询，运行testHQL17
sql = &select abs(m.id),sqrt(m.id),mod(m.id,2) from Msg m&;
8.3使用日期函数查询，运行testHQL18
sql = &select current_date,sysdate,current_timestamp,m.id from Msg m&;
8.4使用日期函数传参查询，运行testHQL19
sql = &from Topic t where t.createDate&:date&;q.setParameter(&date&, new Date());
9.复杂查询
9.1使用group by和having进行分组查询，运行testHQL20
sql = &select t.title,count(*) from Topic t group by t.title&;
sql = &select t.title,count(*) from Topic t group by t.title having count(*)&1&;
9.2使用子查询和exists，运行testHQL21
sql = &from Topic t where t.id&(select avg(t1.id) from Topic t1)&;
sql = &from Topic t where t.id& all(select t1.id from Topic t1 where mod(t1.id,2)=0)&;
sql = &from Topic t where not exists(select m.id from Msg m where m.topic.id=t.id)&;
sql = &from Topic t where exists(select m.id from Msg m where m.topic.id=t.id)&;
9.3使用executeUpdate进行修改和删除操作等，运行testHQL22
sql = &update Topic t set t.title=upper(t.title)&;
q.executeUpdate();
10.其它查询形式
10.1使用NamedQuery进行查询，运行testHQL23
需要先使用annotation进行声明
@NamedQueries({ @NamedQuery(name = &topic.selectCertainTopic&, query = &from Topic t where t.id=:id&) })
Query q = session.getNamedQuery(&topic.selectCertainTopic&);
10.2使用NativeSQL进行查询，运行testHQL24
注意，此时使用的不是hibernate的对象查询，二是使用sql进行查询，类似于JDBC
SQLQuery q = session.createSQLQuery(&select * from category&).addEntity(Category.class);
以上主要探讨了hibernate使用Query进行查询的情况，需要在具体的使用中仔细体会。
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