HIbernate--HQL举例+详解(三)
多表查询
准备数据
增加一个LinkMAN实体类，与Customer形成多对一关系。
public class Customer {
private Long cust_id;
private String cust_name;
private String cust_source;
private String cust_industry;
private String cust_level;
private String cust_linkman;
private String cust_phone;
private String cust_mobile;
//使用set集合,表达一对多关系
private Set<LinkMan> linkMens = new HashSet<LinkMan>();
public Customer() {
}
public Set<LinkMan> getLinkMens() {
return linkMens;
}
public void setLinkMens(Set<LinkMan> linkMens) {
this.linkMens = linkMens;
}
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 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 Customer(Long cust_id, String cust_name, String cust_level) {
super();
this.cust_id = cust_id;
this.cust_name = cust_name;
this.cust_level = cust_level;
}
}
public class LinkMan {
private Long lkm_id;
private Character lkm_gender;
private String lkm_name;
private String lkm_phone;
private String lkm_email;
private String lkm_qq;
private String lkm_mobile;
private String lkm_memo;
private String lkm_position;
//表达多对一关系
private Customer customer ;
public Customer getCustomer() {
return customer;
}
public void setCustomer(Customer customer) {
this.customer = customer;
}
public Long getLkm_id() {
return lkm_id;
}
public void setLkm_id(Long lkm_id) {
this.lkm_id = lkm_id;
}
public Character getLkm_gender() {
return lkm_gender;
}
public void setLkm_gender(Character lkm_gender) {
this.lkm_gender = lkm_gender;
}
public String getLkm_name() {
return lkm_name;
}
public void setLkm_name(String lkm_name) {
this.lkm_name = lkm_name;
}
public String getLkm_phone() {
return lkm_phone;
}
public void setLkm_phone(String lkm_phone) {
this.lkm_phone = lkm_phone;
}
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_mobile() {
return lkm_mobile;
}
public void setLkm_mobile(String lkm_mobile) {
this.lkm_mobile = lkm_mobile;
}
public String getLkm_memo() {
return lkm_memo;
}
public void setLkm_memo(String lkm_memo) {
this.lkm_memo = lkm_memo;
}
public String getLkm_position() {
return lkm_position;
}
public void setLkm_position(String lkm_position) {
this.lkm_position = lkm_position;
}
}
表中数据如下：
内连接和迫切内连接
- 内连接
SQL语句：select * from cst_customer cus,cst_linkman lin where cus.cust_id=lin.lkm_cust_id
hql语句：from Customer c inner join c.linkMens
query.list()返回的list里面每部分是数组形式 - 迫切内连接
迫切内连接和内连接底层实现一样
区别：使用内连接返回list每部分是数组，使用迫切内连接返回list每部分是对象。
hql语句：from Customer c inner join fetch c.linkMens
例子：
//内连接和迫切内连接
@Test
public void fun1(){
Session session = HibernateUtils.openSession();
Transaction tx = session.beginTransaction();
//----------------------------------------------------
String hql1 = " from Customer c inner join c.linkMens ";//内连接
String hql2 = "from Customer c inner join fetch c.linkMens";//迫切内连接
Query query1 = session.createQuery(hql1);
Query query2 = session.createQuery(hql2);
List<Object[]> list1 = query1.list();
List<Customer> list2 = query2.list();
for(Object[] arr : list1){
System.out.println(Arrays.toString(arr));
}
System.out.println(list2);
//----------------------------------------------------
tx.commit();
session.close();
}
运行JUnit测试输出：
Hibernate:
select
customer0_.cust_id as cust_id1_0_0_,
linkmens1_.lkm_id as lkm_id1_1_1_,
customer0_.cust_name as cust_nam2_0_0_,
customer0_.cust_source as cust_sou3_0_0_,
customer0_.cust_industry as cust_ind4_0_0_,
customer0_.cust_level as cust_lev5_0_0_,
customer0_.cust_linkman as cust_lin6_0_0_,
customer0_.cust_phone as cust_pho7_0_0_,
customer0_.cust_mobile as cust_mob8_0_0_,
linkmens1_.lkm_gender as lkm_gend2_1_1_,
linkmens1_.lkm_name as lkm_name3_1_1_,
linkmens1_.lkm_phone as lkm_phon4_1_1_,
linkmens1_.lkm_email as lkm_emai5_1_1_,
linkmens1_.lkm_qq as lkm_qq6_1_1_,
linkmens1_.lkm_mobile as lkm_mobi7_1_1_,
linkmens1_.lkm_memo as lkm_memo8_1_1_,
linkmens1_.lkm_position as lkm_posi9_1_1_,
linkmens1_.lkm_cust_id as lkm_cus10_1_1_
from
cst_customer customer0_
inner join
cst_linkman linkmens1_
on customer0_.cust_id=linkmens1_.lkm_cust_id
Hibernate:
select
customer0_.cust_id as cust_id1_0_0_,
linkmens1_.lkm_id as lkm_id1_1_1_,
customer0_.cust_name as cust_nam2_0_0_,
customer0_.cust_source as cust_sou3_0_0_,
customer0_.cust_industry as cust_ind4_0_0_,
customer0_.cust_level as cust_lev5_0_0_,
customer0_.cust_linkman as cust_lin6_0_0_,
customer0_.cust_phone as cust_pho7_0_0_,
customer0_.cust_mobile as cust_mob8_0_0_,
linkmens1_.lkm_gender as lkm_gend2_1_1_,
linkmens1_.lkm_name as lkm_name3_1_1_,
linkmens1_.lkm_phone as lkm_phon4_1_1_,
linkmens1_.lkm_email as lkm_emai5_1_1_,
linkmens1_.lkm_qq as lkm_qq6_1_1_,
linkmens1_.lkm_mobile as lkm_mobi7_1_1_,
linkmens1_.lkm_memo as lkm_memo8_1_1_,
linkmens1_.lkm_position as lkm_posi9_1_1_,
linkmens1_.lkm_cust_id as lkm_cus10_1_1_,
linkmens1_.lkm_cust_id as lkm_cus10_1_0__,
linkmens1_.lkm_id as lkm_id1_1_0__
from
cst_customer customer0_
inner join
cst_linkman linkmens1_
on customer0_.cust_id=linkmens1_.lkm_cust_id
//内连接，两部分，以数组形式返回
[per.zhang.domain.Customer@48e64352, per.zhang.domain.LinkMan@200606de]
[per.zhang.domain.Customer@48e64352, per.zhang.domain.LinkMan@750fe12e]
[per.zhang.domain.Customer@f8908f6, per.zhang.domain.LinkMan@3e587920]
[per.zhang.domain.Customer@2ef8a8c3, per.zhang.domain.LinkMan@24f43aa3]
[per.zhang.domain.Customer@2ef8a8c3, per.zhang.domain.LinkMan@63fd4873]
[per.zhang.domain.Customer@1e11bc55, per.zhang.domain.LinkMan@7544a1e4]
[per.zhang.domain.Customer@1e11bc55, per.zhang.domain.LinkMan@70e0accd]
[per.zhang.domain.Customer@7957dc72, per.zhang.domain.LinkMan@6ab72419]
//迫切内连接 以对象形式返回，linkMan封装到了Customer的Set集合中
[per.zhang.domain.Customer@48e64352, per.zhang.domain.Customer@48e64352, per.zhang.domain.Customer@f8908f6, per.zhang.domain.Customer@2ef8a8c3, per.zhang.domain.Customer@2ef8a8c3, per.zhang.domain.Customer@1e11bc55, per.zhang.domain.Customer@1e11bc55, per.zhang.domain.Customer@7957dc72]
外连接和迫切外连接
@Test
//外连接和迫切外连接
public void fun2(){
Session session = HibernateUtils.openSession();
Transaction tx = session.beginTransaction();
//----------------------------------------------------
String hql1 = " from Customer c right join c.linkMens ";//右外连接
String hql2 = " from Customer c right join fetch c.linkMens ";//迫切右外连接
Query query1 = session.createQuery(hql1);
Query query2 = session.createQuery(hql2);
List<Object[]> list1 = query1.list();
List<Customer> list2 = query2.list();
for(Object[] arr : list1){
System.out.println(Arrays.toString(arr));
}
System.out.println(list2);
//----------------------------------------------------
tx.commit();
session.close();
}
运行JUnit测试输出：
Hibernate:
select
customer0_.cust_id as cust_id1_0_0_,
linkmens1_.lkm_id as lkm_id1_1_1_,
customer0_.cust_name as cust_nam2_0_0_,
customer0_.cust_source as cust_sou3_0_0_,
customer0_.cust_industry as cust_ind4_0_0_,
customer0_.cust_level as cust_lev5_0_0_,
customer0_.cust_linkman as cust_lin6_0_0_,
customer0_.cust_phone as cust_pho7_0_0_,
customer0_.cust_mobile as cust_mob8_0_0_,
linkmens1_.lkm_gender as lkm_gend2_1_1_,
linkmens1_.lkm_name as lkm_name3_1_1_,
linkmens1_.lkm_phone as lkm_phon4_1_1_,
linkmens1_.lkm_email as lkm_emai5_1_1_,
linkmens1_.lkm_qq as lkm_qq6_1_1_,
linkmens1_.lkm_mobile as lkm_mobi7_1_1_,
linkmens1_.lkm_memo as lkm_memo8_1_1_,
linkmens1_.lkm_position as lkm_posi9_1_1_,
linkmens1_.lkm_cust_id as lkm_cus10_1_1_
from
cst_customer customer0_
right outer join
cst_linkman linkmens1_
on customer0_.cust_id=linkmens1_.lkm_cust_id
Hibernate:
select
customer0_.cust_id as cust_id1_0_0_,
linkmens1_.lkm_id as lkm_id1_1_1_,
customer0_.cust_name as cust_nam2_0_0_,
customer0_.cust_source as cust_sou3_0_0_,
customer0_.cust_industry as cust_ind4_0_0_,
customer0_.cust_level as cust_lev5_0_0_,
customer0_.cust_linkman as cust_lin6_0_0_,
customer0_.cust_phone as cust_pho7_0_0_,
customer0_.cust_mobile as cust_mob8_0_0_,
linkmens1_.lkm_gender as lkm_gend2_1_1_,
linkmens1_.lkm_name as lkm_name3_1_1_,
linkmens1_.lkm_phone as lkm_phon4_1_1_,
linkmens1_.lkm_email as lkm_emai5_1_1_,
linkmens1_.lkm_qq as lkm_qq6_1_1_,
linkmens1_.lkm_mobile as lkm_mobi7_1_1_,
linkmens1_.lkm_memo as lkm_memo8_1_1_,
linkmens1_.lkm_position as lkm_posi9_1_1_,
linkmens1_.lkm_cust_id as lkm_cus10_1_1_,
linkmens1_.lkm_cust_id as lkm_cus10_1_0__,
linkmens1_.lkm_id as lkm_id1_1_0__
from
cst_customer customer0_
right outer join
cst_linkman linkmens1_
on customer0_.cust_id=linkmens1_.lkm_cust_id
//外连接，两部分，以数组形式返回
[pers.zhang.domain.Customer@48e64352, pers.zhang.domain.LinkMan@200606de]
[pers.zhang.domain.Customer@48e64352, pers.zhang.domain.LinkMan@750fe12e]
[pers.zhang.domain.Customer@f8908f6, pers.zhang.domain.LinkMan@3e587920]
[pers.zhang.domain.Customer@2ef8a8c3, pers.zhang.domain.LinkMan@24f43aa3]
[pers.zhang.domain.Customer@2ef8a8c3, pers.zhang.domain.LinkMan@63fd4873]
[pers.zhang.domain.Customer@1e11bc55, pers.zhang.domain.LinkMan@7544a1e4]
[pers.zhang.domain.Customer@1e11bc55, pers.zhang.domain.LinkMan@70e0accd]
[pers.zhang.domain.Customer@7957dc72, pers.zhang.domain.LinkMan@6ab72419]
[null, pers.zhang.domain.LinkMan@3aacf32a]
//外连接，以对象形式返回，linkMan封装到了Customer的Set集合中
[cn.itcast.domain.Customer@48e64352, pers.zhang.domain.Customer@48e64352, cn.itcast.domain.Customer@f8908f6, pers.zhang.domain.Customer@2ef8a8c3, cn.itcast.domain.Customer@2ef8a8c3, pers.zhang.domain.Customer@1e11bc55, cn.itcast.domain.Customer@1e11bc55, pers.zhang.domain.Customer@7957dc72, null]
子查询
对于子查询的数据库，Hibernate支持在查询中使用子查询。一个子查询必须被圆括号包围起来（经常是SQL聚集函数的圆括号）。甚至相互关联的子查询（引用到外部查询中的别名的子查询）也是允许的。
select c.cust_id,c.cust_name,c.cust_level
from Customer c
where c.cust_id = (
select l.customer.cust_id
from LinkMan l
where l.lkm_name like ‘联想02’)
例子：
@Test
//子查询
public void fun4(){
Session session = HibernateUtils.openSession();
Transaction tx = session.beginTransaction();
//----------------------------------------------------
//查询linkman的名字为‘联想02’的customer对象的id，名字，和客户等级
String hql = "select c.cust_id,c.cust_name,c.cust_level "
+ "from Customer c "
+ "where c.cust_id = "
+ "(select l.customer.cust_id "
+ "from LinkMan l "
+ "where l.lkm_name like '联想02')";
Query query = session.createQuery(hql);
List<Object[]> list = query.list();
for(Object[] arr : list){
System.out.println(Arrays.toString(arr));
}
//----------------------------------------------------
tx.commit();
session.close();
}
运行JUnit测试输出：
Hibernate:
select
customer0_.cust_id as col_0_0_,
customer0_.cust_name as col_1_0_,
customer0_.cust_level as col_2_0_
from
cst_customer customer0_
where
customer0_.cust_id=(
select
linkman1_.lkm_cust_id
from
cst_linkman linkman1_
where
linkman1_.lkm_name like '联想02'
)
[2, 联想, 3]