Hibernate 再接触 HQL
Category.java
package com.bjsxt.hibernate; 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; } }
Topic.java
package com.bjsxt.hibernate; import java.util.Date; import javax.persistence.Entity; import javax.persistence.FetchType; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.ManyToOne; @Entity public class Topic { private int id; private String title; private Category category; //private Category category2; private Date createDate; public Date getCreateDate() { return createDate; } public void setCreateDate(Date createDate) { this.createDate = createDate; } @ManyToOne(fetch=FetchType.LAZY) public Category getCategory() { return category; } public void setCategory(Category category) { this.category = category; } @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; } }
Msg
package com.bjsxt.hibernate; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.ManyToOne; @Entity public class Msg { private int id; private String cont; private Topic topic; @ManyToOne public Topic getTopic() { return topic; } public void setTopic(Topic topic) { this.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; } }
Msginfo
package com.bjsxt.hibernate; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.ManyToOne; public class MsgInfo { //VO DTO Value Object username p1 p2 UserInfo->User->DB private int id; private String cont; private String topicName; private String categoryName; public MsgInfo(int id, String cont, String topicName, String categoryName) { super(); this.id = id; this.cont = cont; this.topicName = topicName; this.categoryName = categoryName; } public String getTopicName() { return topicName; } public void setTopicName(String topicName) { this.topicName = topicName; } public String getCategoryName() { return categoryName; } public void setCategoryName(String categoryName) { this.categoryName = categoryName; } 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; } }
Test
test1
@Test public void testHQL_01() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("from Category"); //ql语言 List<Category> categories = (List<Category>)q.list(); //取出对象 for(Category c : categories) { System.out.println(c.getName()); } session.getTransaction().commit(); session.close(); }
@Test
public void testHQL_02() {
Session session = sf.openSession();
session.beginTransaction();
Query q = session.createQuery("from Category c where c.name > 'c5'"); //是对象而不是表名字
List<Category> categories = (List<Category>)q.list(); //返回一个对象数组
for(Category c : categories) {
System.out.println(c.getName());
}
session.getTransaction().commit();
session.close();
}
@Test
public void testHQL_03() {
Session session = sf.openSession();
session.beginTransaction();
Query q = session.createQuery("from Category c order by c.name desc"); //逆序
List<Category> categories = (List<Category>)q.list(); //返回对象数组
for(Category c : categories) {
System.out.println(c.getName());
}
session.getTransaction().commit();
session.close();
}
@Test
public void testHQL_04() {
Session session = sf.openSession();
session.beginTransaction();
Query q = session.createQuery("select distinct c from Category c order by c.name desc"); //没有重复的主键
List<Category> categories = (List<Category>)q.list();
for(Category c : categories) {
System.out.println(c.getName());
}
session.getTransaction().commit();
session.close();
}
@Test
public void testHQL_05() {
Session session = sf.openSession();
session.beginTransaction();
/*Query q = session.createQuery("from Category c where c.id > :min and c.id < :max"); //:相当于占位符
//q.setParameter("min", 2); //设置min值
//q.setParameter("max", 8); //设置max值，也可以用下面这种设法
q.setInteger("min", 2);
q.setInteger("max", 8);*/
Query q = session.createQuery("from Category c where c.id > :min and c.id < :max")
.setInteger("min", 2)
.setInteger("max", 8);
List<Category> categories = (List<Category>)q.list();
for(Category c : categories) {
System.out.println(c.getId() + "-" + c.getName());
}
session.getTransaction().commit();
session.close();
}
@Test
public void testHQL_06() {
Session session = sf.openSession();
session.beginTransaction();
Query q = session.createQuery("from Category c where c.id > ? and c.id < ?"); //另外一种设法
q.setParameter(0, 2)
.setParameter(1, 8);
// q.setParameter(1, 8);
List<Category> categories = (List<Category>)q.list();
for(Category c : categories) {
System.out.println(c.getId() + "-" + c.getName());
}
session.getTransaction().commit();
session.close();
}
//分页
@Test
public void testHQL_07() {
Session session = sf.openSession();
session.beginTransaction();
Query q = session.createQuery("from Category c order by c.name desc");
q.setMaxResults(4); //设置每页的
q.setFirstResult(2); //设置起始
List<Category> categories = (List<Category>)q.list();
for(Category c : categories) {
System.out.println(c.getId() + "-" + c.getName());
}
session.getTransaction().commit();
session.close();
}
@Test
public void testHQL_08() {
Session session = sf.openSession();
session.beginTransaction();
Query q = session.createQuery("select c.id, c.name from Category c order by c.name desc");
List<Object[]> categories = (List<Object[]>)q.list();
for(Object[] o : categories) {
System.out.println(o[0] + "-" + o[1]);
}
session.getTransaction().commit();
session.close();
}
//设定fetch type 为lazy后将不会有第二条sql语句
@Test
public void testHQL_09() {
Session session = sf.openSession();
session.beginTransaction();
Query q = session.createQuery("from Topic t where t.category.id = 1");
List<Topic> topics = (List<Topic>)q.list();
for(Topic t : topics) {
System.out.println(t.getTitle());
//System.out.println(t.getCategory().getName());
}
session.getTransaction().commit();
session.close();
}
//设定fetch type 为lazy后将不会有第二条sql语句
@Test
public void testHQL_10() {
Session session = sf.openSession();
session.beginTransaction();
Query q = session.createQuery("from Topic t where t.category.id = 1");
List<Topic> topics = (List<Topic>)q.list();
for(Topic t : topics) {
System.out.println(t.getTitle());
}
session.getTransaction().commit();
session.close();
}
@Test
public void testHQL_11() {
Session session = sf.openSession();
session.beginTransaction();
Query q = session.createQuery("from Msg m where m.topic.category.id = 1"); //导航 因为有多对一的关系
for(Object o : q.list()) {
Msg m = (Msg)o;
System.out.println(m.getCont());
}
session.getTransaction().commit();
session.close();
}
//了解即可
//VO Value Object
//DTO data transfer object
@Test
public void testHQL_12() {
Session session = sf.openSession();
session.beginTransaction();
Query q = session.createQuery("select new com.bjsxt.hibernate.MsgInfo(m.id, m.cont, m.topic.title, m.topic.category.name) from Msg");
for(Object o : q.list()) {
MsgInfo m = (MsgInfo)o;
System.out.println(m.getCont());
}
session.getTransaction().commit();
session.close();
}
//动手测试left right join
//为什么不能直接写Category名，而必须写t.category
//因为有可能存在多个成员变量（同一个类），需要指明用哪一个成员变量的连接条件来做连接
@Test
public void testHQL_13() {
Session session = sf.openSession();
session.beginTransaction();
Query q = session.createQuery("select t.title, c.name from Topic t join t.category c "); //join Category c
for(Object o : q.list()) {
Object[] m = (Object[])o;
System.out.println(m[0] + "-" + m[1]);
}
session.getTransaction().commit();
session.close();
}
//学习使用uniqueResult
@Test
public void testHQL_14() {
Session session = sf.openSession();
session.beginTransaction();
Query q = session.createQuery("from Msg m where m = :MsgToSearch "); //不重要
Msg m = new Msg();
m.setId(1);
q.setParameter("MsgToSearch", m);
Msg mResult = (Msg)q.uniqueResult(); /返回唯一的一个
System.out.println(mResult.getCont());
session.getTransaction().commit();
session.close();
}
@Test
public void testHQL_15() {
Session session = sf.openSession();
session.beginTransaction();
Query q = session.createQuery("select count(*) from Msg m"); //返回数量
long count = (Long)q.uniqueResult();
System.out.println(count);
session.getTransaction().commit();
session.close();
}
@Test
public void testHQL_16() {
Session session = sf.openSession();
session.beginTransaction();
Query q = session.createQuery("select max(m.id), min(m.id), avg(m.id), sum(m.id) from Msg m");
Object[] o = (Object[])q.uniqueResult();
System.out.println(o[0] + "-" + o[1] + "-" + o[2] + "-" + o[3]);
session.getTransaction().commit();
session.close();
}
@Test
public void testHQL_17() {
Session session = sf.openSession();
session.beginTransaction();
Query q = session.createQuery("from Msg m where m.id between 3 and 5");
for(Object o : q.list()) {
Msg m = (Msg)o;
System.out.println(m.getId() + "-" + m.getCont());
}
session.getTransaction().commit();
session.close();
}
@Test
public void testHQL_18() {
Session session = sf.openSession();
session.beginTransaction();
Query q = session.createQuery("from Msg m where m.id in (3,4, 5)");
for(Object o : q.list()) {
Msg m = (Msg)o;
System.out.println(m.getId() + "-" + m.getCont());
}
session.getTransaction().commit();
session.close();
}
//is null 与 is not null
@Test
public void testHQL_19() {
Session session = sf.openSession();
session.beginTransaction();
Query q = session.createQuery("from Msg m where m.cont is not null");
for(Object o : q.list()) {
Msg m = (Msg)o;
System.out.println(m.getId() + "-" + m.getCont());
}
session.getTransaction().commit();
session.close();
}
pART2
更改Topic
package com.bjsxt.hibernate; import java.util.ArrayList; import java.util.Date; import java.util.List; import javax.persistence.Entity; import javax.persistence.FetchType; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.ManyToOne; import javax.persistence.NamedQueries; import javax.persistence.NamedQuery; import javax.persistence.OneToMany; @Entity @NamedQueries( { @NamedQuery(name="topic.selectCertainTopic", query="from Topic t where t.id = :id") } ) /* @NamedNativeQueries( { @NamedNativeQuery(name="topic.select2_5Topic", query="select * from topic limit 2, 5") } ) */ public class Topic { private int id; private String title; private Category category; private Date createDate; private List<Msg> msgs = new ArrayList<Msg>(); @OneToMany(mappedBy="topic") public List<Msg> getMsgs() { return msgs; } public void setMsgs(List<Msg> msgs) { this.msgs = msgs; } public Date getCreateDate() { return createDate; } public void setCreateDate(Date createDate) { this.createDate = createDate; } @ManyToOne(fetch=FetchType.LAZY) public Category getCategory() { return category; } public void setCategory(Category category) { this.category = category; } @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; } }
@Test public void testHQL_20() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("from Topic t where t.msgs is empty"); for(Object o : q.list()) { Topic t = (Topic)o; System.out.println(t.getId() + "-" + t.getTitle()); } session.getTransaction().commit(); session.close(); } @Test public void testHQL_21() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("from Topic t where t.title like '%5'"); for(Object o : q.list()) { Topic t = (Topic)o; System.out.println(t.getId() + "-" + t.getTitle()); } session.getTransaction().commit(); session.close(); } @Test public void testHQL_22() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("from Topic t where t.title like '_5'"); for(Object o : q.list()) { Topic t = (Topic)o; System.out.println(t.getId() + "-" + t.getTitle()); } session.getTransaction().commit(); session.close(); } //不重要 @Test public void testHQL_23() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("select lower(t.title)," + "upper(t.title)," + "trim(t.title)," + "concat(t.title, '***')," + "length(t.title)" + " from Topic t "); for(Object o : q.list()) { Object[] arr = (Object[])o; System.out.println(arr[0] + "-" + arr[1] + "-" + arr[2] + "-" + arr[3] + "-" + arr[4] + "-"); } session.getTransaction().commit(); session.close(); } @Test public void testHQL_24() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("select abs(t.id)," + "sqrt(t.id)," + "mod(t.id, 2)" + " from Topic t "); for(Object o : q.list()) { Object[] arr = (Object[])o; System.out.println(arr[0] + "-" + arr[1] + "-" + arr[2] ); } session.getTransaction().commit(); session.close(); } @Test public void testHQL_25() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("select current_date, current_time, current_timestamp, t.id from Topic t"); for(Object o : q.list()) { Object[] arr = (Object[])o; System.out.println(arr[0] + " | " + arr[1] + " | " + arr[2] + " | " + arr[3]); } session.getTransaction().commit(); session.close(); } @Test public void testHQL_26() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("from Topic t where t.createDate < :date"); q.setParameter("date", new Date()); for(Object o : q.list()) { Topic t = (Topic)o; System.out.println(t.getTitle()); } session.getTransaction().commit(); session.close(); } @Test public void testHQL_27() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("select t.title, count(*) from Topic t group by t.title") ; for(Object o : q.list()) { Object[] arr = (Object[])o; System.out.println(arr[0] + "|" + arr[1]); } session.getTransaction().commit(); session.close(); } @Test public void testHQL_28() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("select t.title, count(*) from Topic t group by t.title having count(*) >= 1") ; for(Object o : q.list()) { Object[] arr = (Object[])o; System.out.println(arr[0] + "|" + arr[1]); } session.getTransaction().commit(); session.close(); } @Test public void testHQL_29() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("from Topic t where t.id < (select avg(t.id) from Topic t)") ; for(Object o : q.list()) { Topic t = (Topic)o; System.out.println(t.getTitle()); } session.getTransaction().commit(); session.close(); } @Test public void testHQL_30() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("from Topic t where t.id < ALL (select t.id from Topic t where mod(t.id, 2)= 0) ") ; for(Object o : q.list()) { Topic t = (Topic)o; System.out.println(t.getTitle()); } session.getTransaction().commit(); session.close(); } //用in 可以实现exists的功能 //但是exists执行效率高 @Test public void testHQL_31() { Session session = sf.openSession(); session.beginTransaction();// 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)") ; for(Object o : q.list()) { Topic t = (Topic)o; System.out.println(t.getTitle()); } session.getTransaction().commit(); session.close(); } //update and delete //规范并没有说明是不是要更新persistent object，所以如果要使用，建议在单独的trasaction中执行 @Test public void testHQL_32() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.createQuery("update Topic t set t.title = upper(t.title)") ; q.executeUpdate(); q = session.createQuery("from Topic"); for(Object o : q.list()) { Topic t = (Topic)o; System.out.println(t.getTitle()); } session.createQuery("update Topic t set t.title = lower(t.title)") .executeUpdate(); session.getTransaction().commit(); session.close(); } //不重要 @Test public void testHQL_33() { Session session = sf.openSession(); session.beginTransaction(); Query q = session.getNamedQuery("topic.selectCertainTopic"); q.setParameter("id", 5); Topic t = (Topic)q.uniqueResult(); System.out.println(t.getTitle()); session.getTransaction().commit(); session.close(); } //Native（了解） @Test public void testHQL_34() { Session session = sf.openSession(); session.beginTransaction(); SQLQuery q = session.createSQLQuery("select * from category limit 2,4").addEntity(Category.class); List<Category> categories = (List<Category>)q.list(); for(Category c : categories) { System.out.println(c.getName()); } session.getTransaction().commit(); session.close(); } @Test public void testHQL_35() { //尚未实现JPA命名的NativeSQL }
QBC
@Test public void testQBC() { Session session = sf.openSession(); session.beginTransaction(); //criterion 标准/准则/约束 Criteria c = session.createCriteria(Topic.class) //from Topic .add(Restrictions.gt("id", 2)) //greater than = id > 2 .add(Restrictions.lt("id", 8)) //little than = id < 8 .add(Restrictions.like("title", "t_")) .createCriteria("category") .add(Restrictions.between("id", 3, 5)) //category.id >= 3 and category.id <=5 ; //DetachedCriterea for(Object o : c.list()) { Topic t = (Topic)o; System.out.println(t.getId() + "-" + t.getTitle()); } session.getTransaction().commit(); session.close(); }
QBE
@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.setCategory(c); t.setTitle("t" + i); t.setCreateDate(new Date()); session.save(t); } for(int i=0; i<10; i++) { Topic t = new Topic(); t.setId(1); Msg m = new Msg(); m.setCont("m" + i); m.setTopic(t); session.save(m); } session.getTransaction().commit(); session.close(); } //is empty and is not empty //query by criteria query by example @Test public void testQBE() { Session session = sf.openSession(); session.beginTransaction(); Topic tExample = new Topic(); tExample.setTitle("T_"); Example e = Example.create(tExample) .ignoreCase().enableLike(); Criteria c = session.createCriteria(Topic.class) .add(Restrictions.gt("id", 2)) .add(Restrictions.lt("id", 8)) .add(e) ; for(Object o : c.list()) { Topic t = (Topic)o; System.out.println(t.getId() + "-" + t.getTitle()); } session.getTransaction().commit(); session.close(); }
