Hibernate（九）

三套查询之SQL查询

Native Sql Query原生的sql查询.
要求写sql语句.
SQLQuery 是 Query的子类

1.查询所有的学生

    //1.查询所有的学生
    @Test
    public void test1(){
        SQLQuery sqlQuery = session.createSQLQuery("select * from student");//student是表名，不是类名
        sqlQuery.addEntity(Student.class);
        List<Student> list = sqlQuery.list();
        for (Student student : list) {
            System.out.println(student.getId()+student.getName()+student.getTeacher().getTname());
        }
        System.out.println("========================================");
        SQLQuery sqlQuery2 = session.createSQLQuery("select s.* from student s where s.id%2=0");//student是表名，不是类名
        sqlQuery2.addEntity("com.rong.entity.sql.Student");
        List<Student> list2 = sqlQuery2.list();
        for (Student student : list2) {
            System.out.println(student.getId()+student.getName()+student.getTeacher().getTname());
        }
        
    }

2.标量查询

    //2.标量查询
    @Test
    public void test2(){
        SQLQuery sqlQuery = session.createSQLQuery("select s.java,s.math,s.name from student s where s.name like ?");
        sqlQuery.setParameter(0, "%a%");
        List<Object[]> list = sqlQuery.list();
        for (Object[] objects : list) {
            for (Object object : objects) {
                System.out.print(object+"	");
            }
            System.out.println();
        }
        System.out.println("=========================================");
        SQLQuery sqlQuery2 = session.createSQLQuery("select * from student s");
        sqlQuery2.addScalar("s.id");
        sqlQuery2.addScalar("s.name");
        List<Object[]> list2 = sqlQuery2.list();
        for (Object[] objects : list2) {
            for (Object object : objects) {
                System.out.print(object+"	");
            }
            System.out.println();
        }
    }

3.关联查询

    //3.关联查询
    @Test
    public void test3(){
        SQLQuery sqlQuery = session.createSQLQuery("select * from student s,teacher t where s.t_id=t.tid");
        sqlQuery.addEntity("s",Student.class);// 实体查询
        sqlQuery.addEntity("t",Teacher.class);// 实体查询
        sqlQuery.addJoin("t", "s.teacher");// 关联查询 (s.学生持久类中的关联属性)
        /*sqlQuery.addScalar("s.name");// 标量查询
        sqlQuery.addScalar("t.tname");// 标量查询
        List<Object[]> list = sqlQuery.list();
        for (Object[] objects : list) {
            for (Object object : objects) {
                System.out.print(object);
            }
            System.out.println();
        }*/
        List<Object[]> list = sqlQuery.list();
        for (Object[] objects : list) {
            for (Object object : objects) {
                if(object instanceof Student){
                    Student student=(Student) object;
                    System.out.println(student.getId()+student.getName()+student.getTeacher().getTname());
                }else if(object instanceof Teacher){
                    Teacher teacher=(Teacher) object;
                    System.out.println(teacher.getTid()+teacher.getTname());
                }
            }
            System.out.println();
        }
    }

4.命名查询

A.第一种方式*hbm.xml 

1.提供一个配置文件. (xxx.hbm.xml).

2.在hibernate.cfg.xml文件中配置xxx.hbm.xml.

3.定义sql

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping SYSTEM "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd" >
<hibernate-mapping>
    <sql-query name="sql_query">
        select s.*,t.* 
        from student s,teacher t
        where s.t_id=t.tid
                <!-- addEntity: 实体查询 -->
        <return alias="s" class="com.rong.entity.sql.Student"></return>
        <return alias="t" class="com.rong.entity.sql.Teacher"></return>
                <!-- addJoin : 关联查询 -->
        <return-join alias="t" property="s.teacher"></return-join>
                <!-- addScalar : 标量查询 -->
        <return-scalar column="s.name"/>
        <return-scalar column="t.tname"/>
    </sql-query>
</hibernate-mapping>

4.代码

    @Test
    public void test4(){
        Query query = session.getNamedQuery("sql_query");
        List<Object[]> list = query.list();
        for (Object[] objects : list) {
            for (Object object : objects) {
                System.out.println(object);
            }
            System.out.println();
        }
    }

 B.第二种方式: (在持久化类上加注解).

package com.rong.entity.sql;

import javax.persistence.ColumnResult;
import javax.persistence.Entity;
import javax.persistence.EntityResult;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.NamedNativeQueries;
import javax.persistence.NamedNativeQuery;
import javax.persistence.SqlResultSetMapping;

@Entity
//单个SQL语句，一个实体类中该注解只能使用一次
@NamedNativeQuery(name = "sql1", query = "select * from student s,teacher t "
        + "where s.t_id=t.tid",resultClass=Student.class)
//多个SQL语句
@NamedNativeQueries(value = { @NamedNativeQuery(name = "sql2", query = "select * from student s,teacher t where s.t_id=t.tid and s.name like ?"
                    ,resultSetMapping="rs")
                            ,@NamedNativeQuery(name = "sql3", query = "select s.java from student s where s.id>90")})
@SqlResultSetMapping(name = "rs",entities={@EntityResult(entityClass = Student.class)
                                ,@EntityResult(entityClass = Teacher.class)},columns=@ColumnResult(name = "s.name"))
public class Student {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int id;
    private String name;
    private int math;
    private int java;
    @ManyToOne(targetEntity=Teacher.class,fetch=FetchType.LAZY)
    @JoinColumn(name="t_id",referencedColumnName="tid")
    private Teacher teacher;
    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;
    }
    public int getMath() {
        return math;
    }
    public void setMath(int math) {
        this.math = math;
    }
    public int getJava() {
        return java;
    }
    public void setJava(int java) {
        this.java = java;
    }
    public Teacher getTeacher() {
        return teacher;
    }
    public void setTeacher(Teacher teacher) {
        this.teacher = teacher;
    }
}

    @Test
    public void test5(){
        Query query = session.getNamedQuery("sql1");
        List<Student> list = query.list();
        for (Student student : list) {
            System.out.println(student.getName()+student.getTeacher().getTname());
        }
        System.out.println("==============================");
        Query query2 = session.getNamedQuery("sql2");
        query2.setParameter(0, "%a%");
        List<Object[]> list2 = query2.list();
        for (Object[] objects : list2) {
            for (Object object : objects) {
                System.out.println(object);
            }
            System.out.println();
        }
        System.out.println("================================");
        Query query3 = session.getNamedQuery("sql3");
        List<Object> list3 = query3.list();
        for (Object object : list3) {
            System.out.println(object);
        }
    }