hibernate——HQL(二)简单的连接查询、隐式连接、显示连接

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hibernate——HQL(二)简单的连接查询、隐式连接、显示连接

package com.xueyoucto.xueyou;import javax.persistence.*;/** * Created by Administrator on 2016/6/30. */enum Level{   初级,中级,高级}@Entity@Table(name = "h5_teacher")public class Teacher {    @Id    @GeneratedValue(strategy = GenerationType.IDENTITY)    private Integer tid;    private String name;    @Enumerated(EnumType.ORDINAL)    private Level level;    private int age;    public Integer getTid() {        return tid;    }    public void setTid(Integer tid) {        this.tid = tid;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public Level getLevel() {        return level;    }    public void setLevel(Level level) {        this.level = level;    }    public int getAge() {        return age;    }    public void setAge(int age) {        this.age = age;    }}

package com.xueyoucto.xueyou;import org.hibernate.annotations.*;import org.hibernate.annotations.CascadeType;import javax.persistence.*;import javax.persistence.Entity;import javax.persistence.Table;@Entity@Table(name = "h5_user")public class User {    @Id    @GeneratedValue(strategy = GenerationType.IDENTITY)    private Integer id;    private String name;    private Integer age;    private String email;    @ManyToOne(targetEntity = Teacher.class)    @JoinColumn(name = "tid",nullable = false)    @Cascade(CascadeType.ALL)    private Teacher teacher;    public Teacher getTeacher() {        return teacher;    }    public void setTeacher(Teacher teacher) {        this.teacher = teacher;    }    public Integer getId() {        return id;    }    public void setId(Integer id) {        this.id = id;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public Integer getAge() {        return age;    }    public void setAge(Integer age) {        this.age = age;    }    public String getEmail() {        return email;    }    public void setEmail(String email) {        this.email = email;    }}

package com.xueyoucto.xueyou;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.Transaction;import com.xueyoucto.util.HibernateUtil;import java.util.List;/** * Hello world! * */public class App{    public static void main( String[] args )    {        System.out.println( "Hello World!" );        SessionFactory sf = HibernateUtil.getSessionFactory();        Session session = sf.openSession();        Transaction tx = session.beginTransaction();        /*Teacher t = new Teacher();        t.setName("王老师");        t.setAge(35);        t.setLevel(Level.高级);        session.persist(t);*/       /* Teacher t = (Teacher)session.load(Teacher.class,2);        User u = new User();        u.setName("小明4");        u.setAge(13);        u.setEmail("777@qq.com");        u.setTeacher(t);        session.save(u);*/        List userList = session.createQuery("select distinct u from User u where u.teacher.name = ?1")                .setParameter("1","王老师")                .list();        for(Object ele : userList){            User u = (User)ele;            System.out.println(u.getId() + "\t" + u.getName());        }        tx.commit();        session.close();        sf.close();    }}

数据库中表：

h5_teacher

h5_user

运行结果：

上面是进行的隐式连接，还有一种显示连接如下：

List userList = session.createQuery("select distinct u from User u inner join u.teacher t where t.name = ?1")                .setParameter("1","王老师")                .list();        for(Object ele : userList){            User u = (User)ele;            System.out.println(u.getId() + "\t" + u.getName());        }

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