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();
        
    }