Hibernate中使用原生的sql语句进行查询操作

1.  在Hibernate中使用原生的sql语句进行查询操作

2.  使用HQL查询的一般步骤

2.1 一般的用法 addEntity(Student.class)将查询结果转换为实体类

String sql = "";
session.createSQLQuery(sql).addEntity(Student.class).list();

2.2 使用原生SQL语句，查询Student表里面的记录

public void test03() {
Session session = HibernateUtils.openSession();
String sql = "select * from student where id = ?";
List<Student> stus = session.createSQLQuery(sql)//
.addEntity(Student.class)//
.setParameter(0, 1)//
.list();
for (Student stu : stus) {
System.out.println(stu);
}
}

3.  在原生sql语句中，使用DTO的方法

3.1 DTO的定义

package com.hibernate.dto;

import java.math.BigInteger;

public class AgeGroup {
private int age;
private BigInteger count;

public AgeGroup() {
}

public int getAge() {
return age;
}

public void setAge(int age) {
this.age = age;
}

public BigInteger getCount() {
return count;
}

public void setCount(BigInteger count) {
this.count = count;
}

@Override
public String toString() {
return "AgeGroup [age=" + age + ", count=" + count + "]";
}

}

3.2 测试代码

public void test12() {
Session session = HibernateUtils.openSession();
// 按照年龄的分组查询
List<AgeGroup> stus = session
.createSQLQuery(//
"select stu.age , count(*) as count  from student stu group by stu.age")//
.setResultTransformer(Transformers.aliasToBean(AgeGroup.class))//
.list();
// 输出查询结果
for (AgeGroup stu : stus) {
System.out.println("年龄:" + stu.getAge() + " 的人数为:" + stu.getCount());
}
}

4、原生sql语句的连接查询

@Test
public void test14() {
Session session = HibernateUtils.openSession();
// 按照年龄的分组查询
List<Student> stus = session
.createSQLQuery(//
"select stu.*   from student stu join classroom  cla where stu.classid = cla.id and cla.id = ?")//
.addEntity(Student.class).setParameter(0, 1).list();
// 输出查询结果
for (Student stu : stus) {
System.out.println(stu);
}
}