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w# 一.主要内容
Hibernate的各种查询
Hibernate的查询优化
Hibernate小练习
二.基本环境配置
基本结构
Hibernate.cfg.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- 必须的配置 -->
<!-- 配置数据库的基本信息 -->
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql:///hibernatedemo02</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.password">root</property>
<!-- 配置方言 -->
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<!-- 配置可选参数 -->
<!-- 显示SQL语句 -->
<property name="hibernate.show_sql">true</property>
<!-- 格式化SQL语句 -->
<property name="hibernate.format_sql">true</property>
<!-- 自动更新表,可以根据映射文件自动创建表 -->
<property name="hibernate.hbm2ddl.auto">update</property>
<!-- 设置数据库的隔离级别,就使用默认值就OK -->
<property name="hibernate.connection.isolation">4</property>
<!-- 开启绑定本地的session -->
<property name="hibernate.current_session_context_class">thread</property>
<!-- 加载映射文件 -->
<mapping resource="com/fjut/entity/Customer.hbm.xml"/>
<mapping resource="com/fjut/entity/Linkman.hbm.xml"/>
</session-factory>
</hibernate-configuration>
Customer类
public class Customer implements Serializable{
private Long cust_id;
private String cust_name;
private Long cust_user_id;
private Long cust_create_id;
private String cust_source;
private String cust_industry;
private String cust_level;
private String cust_linkman;
private String cust_phone;
private String cust_mobile;
private Set<Linkman> linkmans = new HashSet<Linkman>();
public Customer() {
}
public Customer(Long cust_id, String cust_name, Long cust_user_id, Long cust_create_id, String cust_source,
String cust_industry, String cust_level, String cust_linkman, String cust_phone, String cust_mobile) {
this.cust_id = cust_id;
this.cust_name = cust_name;
this.cust_user_id = cust_user_id;
this.cust_create_id = cust_create_id;
this.cust_source = cust_source;
this.cust_industry = cust_industry;
this.cust_level = cust_level;
this.cust_linkman = cust_linkman;
this.cust_phone = cust_phone;
this.cust_mobile = 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 Long getCust_user_id() {
return cust_user_id;
}
public void setCust_user_id(Long cust_user_id) {
this.cust_user_id = cust_user_id;
}
public Long getCust_create_id() {
return cust_create_id;
}
public void setCust_create_id(Long cust_create_id) {
this.cust_create_id = cust_create_id;
}
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;
}
public Set<Linkman> getLinkmans() {
return linkmans;
}
public void setLinkmans(Set<Linkman> linkmans) {
this.linkmans = linkmans;
}
@Override
public String toString() {
return "Customer [cust_id=" + cust_id + ", cust_name=" + cust_name + ", cust_user_id=" + cust_user_id
+ ", cust_create_id=" + cust_create_id + ", cust_source=" + cust_source + ", cust_industry="
+ cust_industry + ", cust_level=" + cust_level + ", cust_linkman=" + cust_linkman + ", cust_phone="
+ cust_phone + ", cust_mobile=" + cust_mobile + "]";
}
}
Customer.hbm.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="com.fjut.entity.Customer" table="cst_customer">
<id name="cust_id" column="cust_id">
<!-- 设置id自增 -->
<generator class="native"></generator>
</id>
<property name="cust_name" column="cust_name" />
<property name="cust_user_id" column="cust_user_id" />
<property name="cust_create_id" column="cust_create_id" />
<property name="cust_source" column="cust_source" />
<property name="cust_industry" column="cust_industry" />
<property name="cust_level" column="cust_level" />
<property name="cust_linkman" column="cust_linkman" />
<property name="cust_phone" column="cust_phone" />
<property name="cust_mobile" column="cust_mobile" />
<set name="linkmans" inverse="true">
<key column="lkm_cust_id"></key>
<one-to-many class="com.fjut.entity.Linkman"/>
</set>
</class>
</hibernate-mapping>
Linkman类
public class Linkman implements Serializable{
private Long lkm_id;
private String lkm_name;
private String lkm_gender;
private String lkm_phone;
private String lkm_mobile;
private String lkm_email;
private String lkm_qq;
private String lkm_position;
private String lkm_memo;
private Customer customer;
public Linkman() {
}
public Linkman(Long lkm_id, String lkm_name, String lkm_gender, String lkm_phone, String lkm_mobile,
String lkm_email, String lkm_qq, String lkm_position, String lkm_memo, Customer customer) {
super();
this.lkm_id = lkm_id;
this.lkm_name = lkm_name;
this.lkm_gender = lkm_gender;
this.lkm_phone = lkm_phone;
this.lkm_mobile = lkm_mobile;
this.lkm_email = lkm_email;
this.lkm_qq = lkm_qq;
this.lkm_position = lkm_position;
this.lkm_memo = lkm_memo;
this.customer = customer;
}
public Long getLkm_id() {
return lkm_id;
}
public void setLkm_id(Long lkm_id) {
this.lkm_id = lkm_id;
}
public String getLkm_name() {
return lkm_name;
}
public void setLkm_name(String lkm_name) {
this.lkm_name = lkm_name;
}
public String getLkm_gender() {
return lkm_gender;
}
public void setLkm_gender(String lkm_gender) {
this.lkm_gender = lkm_gender;
}
public String getLkm_phone() {
return lkm_phone;
}
public void setLkm_phone(String lkm_phone) {
this.lkm_phone = lkm_phone;
}
public String getLkm_mobile() {
return lkm_mobile;
}
public void setLkm_mobile(String lkm_mobile) {
this.lkm_mobile = lkm_mobile;
}
public String getLkm_email() {
return lkm_email;
}
public void setLkm_email(String lkm_email) {
this.lkm_email = lkm_email;
}
public String getLkm_qq() {
return lkm_qq;
}
public void setLkm_qq(String lkm_qq) {
this.lkm_qq = lkm_qq;
}
public String getLkm_position() {
return lkm_position;
}
public void setLkm_position(String lkm_position) {
this.lkm_position = lkm_position;
}
public String getLkm_memo() {
return lkm_memo;
}
public void setLkm_memo(String lkm_memo) {
this.lkm_memo = lkm_memo;
}
public Customer getCustomer() {
return customer;
}
public void setCustomer(Customer customer) {
this.customer = customer;
}
@Override
public String toString() {
return "Linkman [lkm_id=" + lkm_id + ", lkm_name=" + lkm_name + ", lkm_gender=" + lkm_gender + ", lkm_phone="
+ lkm_phone + ", lkm_mobile=" + lkm_mobile + ", lkm_email=" + lkm_email + ", lkm_qq=" + lkm_qq
+ ", lkm_position=" + lkm_position + ", lkm_memo=" + lkm_memo + "]";
}
}
Linkman.hbm.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="com.fjut.entity.Linkman" table="cst_linkman">
<id name="lkm_id" column="lkm_id">
<generator class="native" />
</id>
<property name="lkm_name" column="lkm_name" />
<property name="lkm_gender" column="lkm_gender" />
<property name="lkm_phone" column="lkm_phone" />
<property name="lkm_mobile" column="lkm_mobile" />
<property name="lkm_email" column="lkm_email" />
<property name="lkm_qq" column="lkm_qq" />
<property name="lkm_position" column="lkm_position" />
<property name="lkm_memo" column="lkm_memo" />
<many-to-one name="customer" class="com.fjut.entity.Customer" column="lkm_cust_id" cascade="save-update"/>
</class>
</hibernate-mapping>
SessionUtils工具类
/**
* Session获取工具类
* @author LGX
*
*/
public class SessionUtils {
private static final Configuration CONFIG;
private static final SessionFactory FACTORY;
static {
CONFIG = new Configuration().configure();//加载hibernate.cfg.xml 配置文件
FACTORY = CONFIG.buildSessionFactory(); //创建SessionFactory
}
/**
* 获取Session,绑定本地Session
* @return
*/
public static Session getCurrentSession() {
return FACTORY.getCurrentSession();
}
}
三.Hibernate 的查询方式
Hibernate中提供了5种检索方式
1.OID检索
2.对象导航检索
3.HQL检索
4.QBC检索
5.SQL检索
OID检索
session.get(对象.class,OID)
例子:
/**
* 1.OID检索
*/
@Test
public void test01() {
Session session = SessionUtils.getCurrentSession();
Transaction tr = session.beginTransaction();
Customer c = session.get(Customer.class, 1L);
System.out.println(c);
trmit();
}
结果:
Hibernate:
select
customer0_.cust_id as cust_id1_0_0_,
customer0_.cust_name as cust_nam2_0_0_,
customer0_.cust_user_id as cust_use3_0_0_,
customer0_.cust_create_id as cust_cre4_0_0_,
customer0_.cust_source as cust_sou5_0_0_,
customer0_.cust_industry as cust_ind6_0_0_,
customer0_.cust_level as cust_lev7_0_0_,
customer0_.cust_linkman as cust_lin8_0_0_,
customer0_.cust_phone as cust_pho9_0_0_,
customer0_.cust_mobile as cust_mo10_0_0_
from
cst_customer customer0_
where
customer0_.cust_id=?
Customer [cust_id=1, cust_name=zhangsan, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
对象导航检索
简单来说就是用查询出来的对象进行下次查询
例子:
/**
* 2.对象导航检索
*/
@Test
public void test02() {
Session session = SessionUtils.getCurrentSession();
Transaction tr = session.beginTransaction();
Customer c = session.get(Customer.class, 1L);
System.out.println("=========================");
System.out.println(c.getLinkmans().size());
trmit();
}
结果:
log4j:WARN No appenders could be found for logger (org.jboss.logging).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache/log4j/1.2/faq.html#noconfig for more info.
Hibernate:
select
customer0_.cust_id as cust_id1_0_0_,
customer0_.cust_name as cust_nam2_0_0_,
customer0_.cust_user_id as cust_use3_0_0_,
customer0_.cust_create_id as cust_cre4_0_0_,
customer0_.cust_source as cust_sou5_0_0_,
customer0_.cust_industry as cust_ind6_0_0_,
customer0_.cust_level as cust_lev7_0_0_,
customer0_.cust_linkman as cust_lin8_0_0_,
customer0_.cust_phone as cust_pho9_0_0_,
customer0_.cust_mobile as cust_mo10_0_0_
from
cst_customer customer0_
where
customer0_.cust_id=?
=========================
Hibernate:
select
linkmans0_.lkm_cust_id as lkm_cus10_1_0_,
linkmans0_.lkm_id as lkm_id1_1_0_,
linkmans0_.lkm_id as lkm_id1_1_1_,
linkmans0_.lkm_name as lkm_name2_1_1_,
linkmans0_.lkm_gender as lkm_gend3_1_1_,
linkmans0_.lkm_phone as lkm_phon4_1_1_,
linkmans0_.lkm_mobile as lkm_mobi5_1_1_,
linkmans0_.lkm_email as lkm_emai6_1_1_,
linkmans0_.lkm_qq as lkm_qq7_1_1_,
linkmans0_.lkm_position as lkm_posi8_1_1_,
linkmans0_.lkm_memo as lkm_memo9_1_1_,
linkmans0_.lkm_cust_id as lkm_cus10_1_1_
from
cst_linkman linkmans0_
where
linkmans0_.lkm_cust_id=?
3
HQL的检索方式
1.基本的查询格式
例子:
/**
* HQL检索
* 基本的查询格式
*/
@Test
public void test03() {
Session session = SessionUtils.getCurrentSession();
Transaction tr = session.beginTransaction();
Query query = session.createQuery("from Customer");
List<Customer> list = query.list();
for (Customer customer : list) {
System.out.println(customer);
}
trmit();
}
结果:
Hibernate:
select
customer0_.cust_id as cust_id1_0_,
customer0_.cust_name as cust_nam2_0_,
customer0_.cust_user_id as cust_use3_0_,
customer0_.cust_create_id as cust_cre4_0_,
customer0_.cust_source as cust_sou5_0_,
customer0_.cust_industry as cust_ind6_0_,
customer0_.cust_level as cust_lev7_0_,
customer0_.cust_linkman as cust_lin8_0_,
customer0_.cust_phone as cust_pho9_0_,
customer0_.cust_mobile as cust_mo10_0_
from
cst_customer customer0_
Customer [cust_id=1, cust_name=zhangsan, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=2, cust_name=zhangsan2, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=3, cust_name=lisi, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=4, cust_name=zhangsan, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
2.使用别名
例子:
/**
* HQL检索
* 起别名
*/
@Test
public void test04() {
Session session = SessionUtils.getCurrentSession();
Transaction tr = session.beginTransaction();
Query query = session.createQuery("select c from Customer c");
List<Customer> list = query.list();
for (Customer customer : list) {
System.out.println(customer);
}
trmit();
}
结果:
Hibernate:
select
customer0_.cust_id as cust_id1_0_,
customer0_.cust_name as cust_nam2_0_,
customer0_.cust_user_id as cust_use3_0_,
customer0_.cust_create_id as cust_cre4_0_,
customer0_.cust_source as cust_sou5_0_,
customer0_.cust_industry as cust_ind6_0_,
customer0_.cust_level as cust_lev7_0_,
customer0_.cust_linkman as cust_lin8_0_,
customer0_.cust_phone as cust_pho9_0_,
customer0_.cust_mobile as cust_mo10_0_
from
cst_customer customer0_
Customer [cust_id=1, cust_name=zhangsan, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=2, cust_name=zhangsan2, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=3, cust_name=lisi, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=4, cust_name=zhangsan, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
3.排序查询
例子:
/**
* HQL检索
* 排序查询
*/
@Test
public void test05() {
Session session = SessionUtils.getCurrentSession();
Transaction tr = session.beginTransaction();
Query query = session.createQuery("select c from Customer c order by c.cust_id desc");
List<Customer> list = query.list();
for (Customer customer : list) {
System.out.println(customer);
}
trmit();
}
结果:
Hibernate:
select
customer0_.cust_id as cust_id1_0_,
customer0_.cust_name as cust_nam2_0_,
customer0_.cust_user_id as cust_use3_0_,
customer0_.cust_create_id as cust_cre4_0_,
customer0_.cust_source as cust_sou5_0_,
customer0_.cust_industry as cust_ind6_0_,
customer0_.cust_level as cust_lev7_0_,
customer0_.cust_linkman as cust_lin8_0_,
customer0_.cust_phone as cust_pho9_0_,
customer0_.cust_mobile as cust_mo10_0_
from
cst_customer customer0_
order by
customer0_.cust_id desc
Customer [cust_id=4, cust_name=zhangsan, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=3, cust_name=lisi, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=2, cust_name=zhangsan2, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=1, cust_name=zhangsan, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
4.分页查询
例子:
/**
* HQL检索
* 分页查询
*/
@Test
public void test06() {
Session session = SessionUtils.getCurrentSession();
Transaction tr = session.beginTransaction();
Query query = session.createQuery("from Customer");
query.setFirstResult(0);//从第一条记录开始
query.setMaxResults(2);//最大查询两条
List<Customer> list = query.list();
for (Customer customer : list) {
System.out.println(customer);
}
trmit();
}
结果:
Hibernate:
select
customer0_.cust_id as cust_id1_0_,
customer0_.cust_name as cust_nam2_0_,
customer0_.cust_user_id as cust_use3_0_,
customer0_.cust_create_id as cust_cre4_0_,
customer0_.cust_source as cust_sou5_0_,
customer0_.cust_industry as cust_ind6_0_,
customer0_.cust_level as cust_lev7_0_,
customer0_.cust_linkman as cust_lin8_0_,
customer0_.cust_phone as cust_pho9_0_,
customer0_.cust_mobile as cust_mo10_0_
from
cst_customer customer0_ limit ?
Customer [cust_id=1, cust_name=zhangsan, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=2, cust_name=zhangsan2, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
5.带条件的查询
例子:
/**
* HQL检索
* 带条件的查询
*/
@Test
public void test07() {
Session session = SessionUtils.getCurrentSession();
Transaction tr = session.beginTransaction();
//使用?作为占位符
Query query = session.createQuery("from Customer where cust_id = ?");
query.setParameter(0, 1L);
List<Customer> list = query.list();
for (Customer customer : list) {
System.out.println(customer);
}
System.out.println("================================================");
//使用字符串作为占位符
Query query2 = session.createQuery("from Customer where cust_id = :id");
query2.setParameter("id", 3L);
List<Customer> list2 = query2.list();
for (Customer customer : list2) {
System.out.println(customer);
}
trmit();
}
结果:
Hibernate:
select
customer0_.cust_id as cust_id1_0_,
customer0_.cust_name as cust_nam2_0_,
customer0_.cust_user_id as cust_use3_0_,
customer0_.cust_create_id as cust_cre4_0_,
customer0_.cust_source as cust_sou5_0_,
customer0_.cust_industry as cust_ind6_0_,
customer0_.cust_level as cust_lev7_0_,
customer0_.cust_linkman as cust_lin8_0_,
customer0_.cust_phone as cust_pho9_0_,
customer0_.cust_mobile as cust_mo10_0_
from
cst_customer customer0_
where
customer0_.cust_id=?
Customer [cust_id=1, cust_name=zhangsan, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
================================================
Hibernate:
select
customer0_.cust_id as cust_id1_0_,
customer0_.cust_name as cust_nam2_0_,
customer0_.cust_user_id as cust_use3_0_,
customer0_.cust_create_id as cust_cre4_0_,
customer0_.cust_source as cust_sou5_0_,
customer0_.cust_industry as cust_ind6_0_,
customer0_.cust_level as cust_lev7_0_,
customer0_.cust_linkman as cust_lin8_0_,
customer0_.cust_phone as cust_pho9_0_,
customer0_.cust_mobile as cust_mo10_0_
from
cst_customer customer0_
where
customer0_.cust_id=?
Customer [cust_id=3, cust_name=lisi, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
6.投影查询
投影查询返回的是一个Object数组
可以使用fetch迫切查询
1)普通查询
例子:
/**
* HQL检索
* 投影查询
*/
@Test
public void test08() {
Session session = SessionUtils.getCurrentSession();
Transaction tr = session.beginTransaction();
//使用?作为占位符
Query query = session.createQuery("select cust_id,cust_name from Customer");
List<Object[]> list = query.list();
for (Object[] objects : list) {
for (Object object : objects) {
System.out.print(object + " ");
}
System.out.println();
}
trmit();
}
结果:
Hibernate:
select
customer0_.cust_id as col_0_0_,
customer0_.cust_name as col_1_0_
from
cst_customer customer0_
1 zhangsan
2 zhangsan2
3 lisi
4 zhangsan
2)可以将查询结果封装到对象中
HQL:select new Customer(cust_id,cust_name) from Customer
例子:
/**
* HQL检索
* 投影查询
* 注:使用封装对象的方法首先要提供对应的构造函数
public Customer(Long cust_id, String cust_name) {
this.cust_id = cust_id;
this.cust_name = cust_name;
}
*/
@Test
public void test08() {
Session session = SessionUtils.getCurrentSession();
Transaction tr = session.beginTransaction();
Query query = session.createQuery("select new Customer(cust_id,cust_name) from Customer");
List<Customer> list = query.list();
for (Customer customer : list) {
System.out.println(customer);
}
trmit();
}
结果:
Hibernate:
select
customer0_.cust_id as col_0_0_,
customer0_.cust_name as col_1_0_
from
cst_customer customer0_
Customer [cust_id=1, cust_name=zhangsan, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=2, cust_name=zhangsan2, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=3, cust_name=lisi, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=4, cust_name=zhangsan, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
3)聚合函数查询
可以使用SQL语法内的聚合函数,但是不同的是Hibernate 内不能使用 * 来代替所有
例如:
SQL: select count(*) from cust
HQL: select count(cust_id) from cust 要用具体属性
例子:
/**
* HQL检索
* 投影查询
* 聚合函数的使用
*/
@Test
public void test09() {
Session session = SessionUtils.getCurrentSession();
Transaction tr = session.beginTransaction();
Query query = session.createQuery("select count(cust_id) from Customer");
List<Number> list = query.list();
System.out.println(list.get(0).intValue());
trmit();
}
结果:
Hibernate:
select
count(customer0_.cust_id) as col_0_0_
from
cst_customer customer0_
4
QBC的检索方式
简单的查询
/**
* QBC查询
*/
@SuppressWarnings("all")
@Test
public void test10() {
//1.创建Session
Session session = SessionUtils.getCurrentSession();
//2.开启事务
Transaction tr = session.beginTransaction();
//3.创建criteria
Criteria criteria = session.createCriteria(Customer.class);
List<Customer> lisy = criteria.list();
for (Customer customer : lisy) {
System.out.println(customer);
}
trmit();
}
结果:
Hibernate:
select
this_.cust_id as cust_id1_0_0_,
this_.cust_name as cust_nam2_0_0_,
this_.cust_user_id as cust_use3_0_0_,
this_.cust_create_id as cust_cre4_0_0_,
this_.cust_source as cust_sou5_0_0_,
this_.cust_industry as cust_ind6_0_0_,
this_.cust_level as cust_lev7_0_0_,
this_.cust_linkman as cust_lin8_0_0_,
this_.cust_phone as cust_pho9_0_0_,
this_.cust_mobile as cust_mo10_0_0_
from
cst_customer this_
Customer [cust_id=1, cust_name=zhangsan, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=2, cust_name=zhangsan2, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=3, cust_name=lisi, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=4, cust_name=zhangsan, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
条件查询
@SuppressWarnings("all")
@Test
public void test11() {
Session session = SessionUtils.getCurrentSession();
Transaction tr = session.beginTransaction();
Criteria criteria = session.createCriteria(Customer.class);
//查找Id等于1的人
criteria.add(Restrictions.eq("cust_id", 1L));
List<Customer> list = criteria.list();
for (Customer customer : list) {
System.out.println(customer);
}
trmit();
}
结果:
Hibernate:
select
this_.cust_id as cust_id1_0_0_,
this_.cust_name as cust_nam2_0_0_,
this_.cust_user_id as cust_use3_0_0_,
this_.cust_create_id as cust_cre4_0_0_,
this_.cust_source as cust_sou5_0_0_,
this_.cust_industry as cust_ind6_0_0_,
this_.cust_level as cust_lev7_0_0_,
this_.cust_linkman as cust_lin8_0_0_,
this_.cust_phone as cust_pho9_0_0_,
this_.cust_mobile as cust_mo10_0_0_
from
cst_customer this_
where
this_.cust_id=?
Customer [cust_id=1, cust_name=zhangsan, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
例子2:
@SuppressWarnings("all")
@Test
public void test11() {
Session session = SessionUtils.getCurrentSession();
Transaction tr = session.beginTransaction();
Criteria criteria = session.createCriteria(Customer.class);
//查找名字中含有z的人
criteria.add(Restrictions.ilike("cust_name", "%z%"));
List<Customer> list = criteria.list();
for (Customer customer : list) {
System.out.println(customer);
}
trmit();
}
结果:
Hibernate:
select
this_.cust_id as cust_id1_0_0_,
this_.cust_name as cust_nam2_0_0_,
this_.cust_user_id as cust_use3_0_0_,
this_.cust_create_id as cust_cre4_0_0_,
this_.cust_source as cust_sou5_0_0_,
this_.cust_industry as cust_ind6_0_0_,
this_.cust_level as cust_lev7_0_0_,
this_.cust_linkman as cust_lin8_0_0_,
this_.cust_phone as cust_pho9_0_0_,
this_.cust_mobile as cust_mo10_0_0_
from
cst_customer this_
where
lower(this_.cust_name) like ?
Customer [cust_id=1, cust_name=zhangsan, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=2, cust_name=zhangsan2, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=4, cust_name=zhangsan, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
分页查询
//设置开始查询位置
criteria.setFirstResult(0);
//设置最大查询长度
criteria.setMaxResults(2);
例子:
@SuppressWarnings("all")
@Test
public void test11() {
Session session = SessionUtils.getCurrentSession();
Transaction tr = session.beginTransaction();
Criteria criteria = session.createCriteria(Customer.class);
//设置开始查询位置
criteria.setFirstResult(0);
//设置最大查询长度
criteria.setMaxResults(2);
List<Customer> list = criteria.list();
for (Customer customer : list) {
System.out.println(customer);
}
trmit();
}
结果:
Hibernate:
select
this_.cust_id as cust_id1_0_0_,
this_.cust_name as cust_nam2_0_0_,
this_.cust_user_id as cust_use3_0_0_,
this_.cust_create_id as cust_cre4_0_0_,
this_.cust_source as cust_sou5_0_0_,
this_.cust_industry as cust_ind6_0_0_,
this_.cust_level as cust_lev7_0_0_,
this_.cust_linkman as cust_lin8_0_0_,
this_.cust_phone as cust_pho9_0_0_,
this_.cust_mobile as cust_mo10_0_0_
from
cst_customer this_ limit ?
Customer [cust_id=1, cust_name=zhangsan, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=2, cust_name=zhangsan2, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
排序查询
criteria.addOrder(Order.desc(“cust_id”));
例子:
@SuppressWarnings("all")
@Test
public void test11() {
Session session = SessionUtils.getCurrentSession();
Transaction tr = session.beginTransaction();
Criteria criteria = session.createCriteria(Customer.class);
//按照cust_id 降序
criteria.addOrder(Order.desc("cust_id"));
List<Customer> list = criteria.list();
for (Customer customer : list) {
System.out.println(customer);
}
trmit();
}
结果:
Hibernate:
select
this_.cust_id as cust_id1_0_0_,
this_.cust_name as cust_nam2_0_0_,
this_.cust_user_id as cust_use3_0_0_,
this_.cust_create_id as cust_cre4_0_0_,
this_.cust_source as cust_sou5_0_0_,
this_.cust_industry as cust_ind6_0_0_,
this_.cust_level as cust_lev7_0_0_,
this_.cust_linkman as cust_lin8_0_0_,
this_.cust_phone as cust_pho9_0_0_,
this_.cust_mobile as cust_mo10_0_0_
from
cst_customer this_
order by
this_.cust_id desc
Customer [cust_id=4, cust_name=zhangsan, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=3, cust_name=lisi, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=2, cust_name=zhangsan2, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
Customer [cust_id=1, cust_name=zhangsan, cust_user_id=null, cust_create_id=null, cust_source=null, cust_industry=null, cust_level=null, cust_linkman=null, cust_phone=null, cust_mobile=null]
聚合查询
QBC的聚合函数查询,使用setProjection尽行聚合查询
criteria.setProjection(Projections.max(“cust_id”));
例子:
@SuppressWarnings("all")
@Test
public void test11() {
Session session = SessionUtils.getCurrentSession();
Transaction tr = session.beginTransaction();
Criteria criteria = session.createCriteria(Customer.class);
//查询最大的id值
criteria.setProjection(Projections.max("cust_id"));
List<Number> list = criteria.list();
System.out.println(list.get(0).intValue());
trmit();
}
结果:
Hibernate:
select
max(this_.cust_id) as y0_
from
cst_customer this_
4
离线查询
离线条件查询使用的是DetachedCriteria接口进行查询,离线条件查询对象在创建的时候,不需要使用Session对象,只是在查询的时候使用Session对象即可
例子:
@Test
public void test12() {
//1.获得离线条件查询的对象
DetachedCriteria detachedCriteria = DetachedCriteria.forClass(Customer.class);
//2.添加查询条件
detachedCriteria.add(Restrictions.eq("cust_id", 1L));
//3.获取session
Session session = SessionUtils.getCurrentSession();
Transaction tr = session.beginTransaction();
//4.获取criteria对象
Criteria criteria = detachedCriteria.getExecutableCriteria(session);
//5.执行
List<Customer> list = criteria.list();
for (Customer customer : list) {
System.out.println(customer);
}
trmit();
}
多表查询
SQL检索方式
四.Hibernate的查询策略
略
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