Hibernate中使用原生的sql语句进行查询操作

红太狼 2022-09-24 01:24 67阅读 0赞

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);
    		}
    	}