Hibernate的HQL总结
ＨＱＬ建立于对象的概念上，与ＭＹＳＱＬ 的SQL语句有点不太一样，但是，大部分还是一样！现收集网络资源以供以后方便查找！
以个普通Users表为例：
建表语句：
CREATE DATABASE `interceptor`
CHARACTER SET 'utf8';
USE `interceptor`;
DROP TABLE IF EXISTS `users`;
create table users(
id int auto_increment primary key,
name varchar(10) not null,
passwd varchar(10) not null
)
ENGINE=InnoDB DEFAULT CHARSET=utf8;
User.java:
package com.domain;
public class Users implements java.io.Serializable {
private Integer id;
private String name;
private String passwd;
public Users() {
}
public Users(String name, String passwd) {
this.name = name;
this.passwd = passwd;
}
public Integer getId() {
return this.id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
public String getPasswd() {
return this.passwd;
}
public void setPasswd(String passwd) {
this.passwd = passwd;
}
User.hbm.xml:
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="com.domain.Users" table="users" catalog="interceptor">
<id name="id" type="java.lang.Integer">
<column name="id" />
<generator class="native" />
</id>
<property name="name" type="java.lang.String">
<column name="name" length="10" not-null="true" />
</property>
<property name="passwd" type="java.lang.String">
<column name="passwd" length="10" not-null="true" />
</property>
</class>
</hibernate-mapping>
1. 查询整个映射对象所有字段
//直接from查询出来的是一个映射对象，即：查询整个映射对象所有字段
String hql = "from Users";
Query query = session.createQuery(hql);
List<Users> users = query.list();
for(Users user : users){
System.out.println(user.getName() + " : " + user.getPasswd() + " : " + user.getId());
}
输出结果为：
name1 : password1 : 1
name2 : password2 : 2
name3 : password3 : 3
2.查询单个字段
String hql = " select name from Users";
Query query = session.createQuery(hql);
List<String> list = query.list();
for(String str : list){
System.out.println(str);
}
输出结果为：
name1
name2
name3
3.查询其中几个字段
String hql = " select name,passwd from Users";
Query query = session.createQuery(hql);
//默认查询出来的list里存放的是一个Object数组
List<Object[]> list = query.list();
for(Object[] object : list){
String name = (String)object[0];
String passwd = (String)object[1];
System.out.println(name + " : " + passwd);
}
输出结果为：
name1 : password1
name2 : password2
name3 : password3
4.修改默认查询结果(query.list())不以Object[]数组形式返回，以List形式返回
//查询其中几个字段,添加new list(),注意list里的l是小写的。也不需要导入包，这样通过query.list()出来的list里存放的不再是默认的Object数组了，而是List集合了
String hql = " select new list(name,passwd) from Users";
Query query = session.createQuery(hql);
//默认查询出来的list里存放的是一个Object数组，但是在这里list里存放的不再是默认的Object数组了，而是List集合了
List<List> list = query.list();
for(List user : list){
String name = (String)user.get(0);
String passwd = (String)user.get(1);
System.out.println(name + " : " + passwd);
}
输出结果为：
name1 : password1
name2 : password2
name3 : password3
5.修改默认查询结果(query.list())不以Object[]数组形式返回，以Map形式返回
//查询其中几个字段,添加new map(),注意map里的m是小写的。也不需要导入包，这样通过query.list()出来的list里存放的不再是默认的Object数组了，而是map集合了
String hql = " select new map(name,passwd) from Users";
Query query = session.createQuery(hql);
//默认查询出来的list里存放的是一个Object数组，但是在这里list里存放的不再是默认的Object数组了，而是Map集合了
List<Map> list = query.list();
for(Map user : list){
//一条记录里所有的字段值都是map里的一个元素,key是字符串0,1,2,3....，value是字段值
//如果将hql改为：String hql = " select new map(name as username,passwd as password) from Users";,那么key将不是字符串0,1,2...了，而是"username","password"了
String name = (String)user.get("0");//get("0");是get(key),注意:0,1,2...是字符串，而不是整形
String passwd = (String)user.get("1");
System.out.println(name + " : " + passwd);
}
输出结果为：
name1 : password1
name2 : password2
name3 : password3
6.修改默认查询结果以Set形式返回,但是因为Set里是不允许有重复的元素，所以:username和password的值不能相同。只需将hql改为：String
hql = " select new set(name,passwd) from Users";
7.修改默认查询结果(query.list())不以Object[]数组形式返回，以自定义类型返回
自定义类：
package com.domain;
public class MyUser {
private String username;
private String password;
//因为：String hql = " select new com.domain.MyUser(name,passwd) from Users";所以必须要有接受2个参数的构造函数
public MyUser(String username,String password){
this.username = username;
this.password = password;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
String hql = "from Users";中的Users类也是必须加包名的，但是因为再Users.hbm.xml里<hibernate-mapping auto-import="true"> auto-import默认值为true（所以auto-import属性也可以不写）,自动导入了
String hql = " select new com.domain.MyUser(name,passwd) from Users";
Query query = session.createQuery(hql);
//默认查询出来的list里存放的是一个Object数组，但是在这里list里存放的不再是默认的Object数组了，而是MyUser对象了
List<MyUser> myUsers = query.list();
for(MyUser myUser : myUsers){
String name = myUser.getUsername();
String passwd = myUser.getPassword();
System.out.println(name + " : " + passwd);
}
输出结果为：
name1 : password1
name2 : password2
name3 : password3
8：条件查询
//条件查询，参数索引值从0开始，索引位置。通过setString,setParameter设置参数
String hql = "from Users where name=? and passwd=?";
Query query = session.createQuery(hql);
//第1种方式
// query.setString(0, "name1");
// query.setString(1, "password1");
//第2种方式
query.setParameter(0, "name1",Hibernate.STRING);
query.setParameter(1, "password1",Hibernate.STRING);
List<Users> list = query.list();
for(Users users : list){
System.out.println(users.getId());
}
//条件查询，自定义索引名(参数名):username,:password.通过setString,setParameter设置参数
String hql = "from Users where name=:username and passwd=:password";
Query query = session.createQuery(hql);
//第1种方式
// query.setString("username", "name1");
// query.setString("password", "password1");
//第2种方式,第3个参数确定类型
query.setParameter("username", "name1",Hibernate.STRING);
query.setParameter("password", "password1",Hibernate.STRING);
List<Users> list = query.list();
for(Users users : list){
out.println(users.getId());
}
//条件查询,通过setProperties设置参数
String hql = "from Users where name=:username and passwd=:password";
Query query = session.createQuery(hql);
//MyUser类的2个属性必须和:username和:password对应
MyUser myUser = new MyUser("name1","password1");
query.setProperties(myUser);
List<Users> list = query.list();
for(Users users : list){
System.out.println(users.getId());
}
支持谓词in，需要使用setParameterList进行参数传递
List students = session.createQuery("select s.id, s.name from Student s where s.id in(:myids)").setParameterList("myids", new Object[]{1, 2, 3, 4, 5}).list();
for (Iterator iter=students.iterator(); iter.hasNext();) {
Object[] obj = (Object[])iter.next();
System.out.println(obj[0] + "," + obj[1]);
}
在HQL中使用数据库的函数
List students = session.createQuery("select s.id, s.name from Student s where date_format(s.createTime, '%Y-%m')=?").setParameter(0, "2010-12").list();
for (Iterator iter=students.iterator(); iter.hasNext();) {
Object[] obj = (Object[])iter.next();
System.out.println(obj[0] + "," + obj[1]);
}
6.查询时间段的数据
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
List students = session.createQuery("select s.id, s.name from Student s where s.createTime between ? and ?").setParameter(0, sdf.parse("2010-12-01 00:00:00")).setParameter(1, sdf.parse("2010-12-31 23:59:59")).list();
for (Iterator iter=students.iterator(); iter.hasNext();) {
Object[] obj = (Object[])iter.next();
System.out.println(obj[0] + "," + obj[1]);
}
原生sql测试
List students = session.createSQLQuery("select * from t_student").list();
多表连接
测试查询有配置多对多关系的对象
@SuppressWarnings("unchecked")
public void test1()
Session session = sessionFactory.openSession();
session.beginTransaction();
String hql = "select s from Student s join s.courses c where s.name like '%micmiu.com%' and c.name ='math'";
String hql2 = "select s from Student s,Course c where c.id in elements (s.courses) and s.name like '%micmiu.com%' and c.name ='math'";
Query query = session.createQuery(hql);
List<Student> list = query.list();
System.out.println("----------- size:" + list.size());
Assert.assertEquals(1, list.size());
for (Student s : list) {
Assert.assertEquals("micmiu.com", s.getName());
System.out.println(s);
}
session.getTransaction().commit();
session.close();
}
测试查询无配置多对多关系的对象
@SuppressWarnings("unchecked")
public void test2() {
Session session = sessionFactory.openSession();
session.beginTransaction();
String hql = "select distinct c from Student s,Course c where c.id in elements (s.courses) and s.name like '%micmiu.com%' and c.name ='math'";
Query query = session.createQuery(hql);
List<Course> list = query.list();
System.out.println("----------- size:" + list.size());
Assert.assertEquals(1, list.size());
for (Course c : list) {
Assert.assertEquals("math", c.getName());
System.out.println(c);
}
session.getTransaction().commit();
session.close();
}
}
order by 语句
@Test
public void testHQL_3() {
Session s = sf.getCurrentSession();
s.beginTransaction();
Query query = s.createQuery("from Category c order by c.name desc");
List<Category> cs = query.list();
for(Category c : cs) {
System.out.println(c.getName());
}
s.getTransaction().commit();
}
排序desc/asc
@Test
public void testHQL_4() {
Session session = sf.getCurrentSession();
session.beginTransaction();
Query q = session.createQuery("select distinct c from Category c order by c.name desc");
List<Category> cs = (List<Category>)q.list();
for(Category c : cs) {
System.out.println(c.getName());
}
session.getTransaction().commit();
}
实体类中有关系的查询（对象导航）
@Test
public void testHQL_10() {
Session s = sf.getCurrentSession();
s.beginTransaction();
Query q = s.createQuery("from Topic t where t.category.id = 1");
List<Topic> ts = (List<Topic>)q.list();
for(Topic t : ts) {
System.out.println(t.getId() + " = " + t.getCategory().getName());
}
s.getTransaction().commit();
}
@Test
public void testHQL_11() {
Session s = sf.getCurrentSession();
s.beginTransaction();
Query q = s.createQuery("from Msg m where m.topic.category.id = 1");
List<Msg> ms = (List<Msg>)q.list();
for(Msg m : ms) {
System.out.println(m.getCont());
}
s.getTransaction().commit();
}
NOT NULL 查询条件
@Test
public void testHQL_18() {
Session s = sf.getCurrentSession();
s.beginTransaction();
Query q = s.createQuery("from Msg m where m.cont is not null");
List<Msg> cs = (List<Msg>)q.list();
for(Msg c : cs) {
System.out.println(c.getId() + " - " + c.getCont());
}
s.getTransaction().commit();
}
Query q = session.createQuery("from Msg m where m.cont is not null");
Query q = session.createQuery("from Topic t where t.msgs is empty")
Having查询
@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();
}
嵌套查询
@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();
}
函数查询使用
@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();
}
other
Java代码
Query q = session.createQuery("select lower(t.title),"
+ "upper(t.title)," + "trim(t.title),"
+ "concat(t.title, '***')," + "length(t.title)"
+ " from Topic t ");
Query q = session.createQuery("select abs(t.id)," + "sqrt(t.id),"
+ "mod(t.id, 2)" + " from Topic t ");
Query q = session
.createQuery("select current_date, current_time, current_timestamp, t.id from Topic t");
Query q = session
.createQuery("from Topic t where t.createDate < :date");
q.setParameter("date", new Date());
Query q = session
.createQuery("select t.title, count(*) from Topic t group by t.title having count(*) >= 1");
Query q = session
.createQuery("from Topic t where t.id < (select avg(t.id) from Topic t)");
Query q = session
.createQuery("from Topic t where t.id < ALL (select t.id from Topic t where mod(t.id, 2)= 0) ");
// 用in 可以实现exists的功能
// 但是exists执行效率高
// t.id not in (1)
Query q = session
.createQuery("from Topic t where not exists (select m.id from Msg m where m.topic.id=t.id)");
// Query q =
// session.createQuery("from Topic t where exists (select m.id from Msg m where m.topic.id=t.id)")