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+"\t");
             }
             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+"\t");
             }
             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);
         }
     }