Hibernate支持三種查詢語言：HQL查詢、Criteria查詢和原生SQL查詢

HQL(hibernate Query Language，hibernate查詢語言)是一種面向對象查詢語言，其中沒有表和字段的概念，只有類、對象和屬性的概念

語法：

　　form子句：form +全類名 / form + 類名（查詢所有）

　　select子句：select dept.deptname from Dept

　　where子句：from dept where deptName=‘sales‘;

HQL執行語句

　　　例子：form子句、select子句、where子句以及參數查詢

　　　　建立實體類

public class Dept {
    private Integer deptno;
    private String dname;

    public Dept() {
    }

    public Dept(Integer deptno, String dname) {
        this.deptno = deptno;
        this.dname = dname;
    }

    public Integer getDeptno() {
        return deptno;
    }

    
 
public void setDeptno(Integer deptno) {
        this.deptno = deptno;
    }

    public String getDname() {
        return dname;
    }

    public void setDname(String dname) {
        this.dname = dname;
    }
}

測試方法

package cn;

import cn.happy.entity.Dog;
import cn.hib.entity.Dept;
import org.hibernate.Query;
 
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.junit.Before;
import org.junit.Test;

import java.util.List;

/**
 * Created by a on 2017/8/20.
 */
public class Test924 {
    Configuration cfg;
    SessionFactory factory;
    Session session;
    Transaction tx;

    @Before
    public void beforeTest(){
        //創建配置對象
        cfg=new Configuration().configure();
        //根據配置對象創建SessonFactory
        factory=cfg.buildSessionFactory();
        //根據SessionFactory創建Session
        session=factory.getCurrentSession();
        //session=factory.openSession();
        //開啟事務
        tx=session.beginTransaction();
    }

    @Test
    public void testlist(){
        String hql="from Dept";
        Query query=session.createQuery(hql);
        List<Dept> list=query.list();
        for (Dept dept : list){
            System.out.println(dept.getDname());
        }
    }
    @Test
    public void selectSomeColumnFromTable(){
        String hql="select dept.deptno,dept.dname from Dept";
        Query query=session.createQuery(hql);
        List<Object[]>list=query.list();
        for(Object[] obj : list){
            for (Object child : obj){
                System.out.println(child);
            }
        }
    }
    @Test
    public void selectSomesColumnFromTable(){
        String hql="select new Dept(dept.deptno,dept.dname) from Dept dept";
        Query query=session.createQuery(hql);
        List<Dept> list=query.list();
        for (Dept dept : list){
            System.out.println(dept.getDname());
        }
    }
    @Test
    public void selectSomeRecordsFromTable(){
        String hql="from dept.deptno,dept.dname from Dept dept where dept.dname=‘RESEARCH‘";
        Query query=session.createQuery(hql);
        List<Dept> list=query.list();
        for (Dept dept : list){
            System.out.println(dept.getDname());
        }
    }

    //案例：參數查詢： 方案一：匿名占位符“?”
    @Test
    public void selectByConditionNiming(){
        String hql="from Dept dept where dname=?";
        Query query=session.createQuery(hql);
        query.setParameter(0,"RESEARCH");
        List<Dept> list=query.list();
        for(Dept dept : list){
            System.out.println(dept.getDname());
        }
    }

    //案例：參數查詢：方案二：
    @Test
    public void selectByConditionParametername(){
        String hql="from Dept dept where dname=:dname";
        Query query=session.createQuery(hql);
        query.setParameter("dname","RESEARCH");
        List<Dept> list=query.list();
        for(Dept dept : list){
            System.out.println(dept.getDname());
        }
    }
    //案例：參數查詢：方案三：name 參數名稱綁定++++對象屬性
    @Test
    public void selectByConditionParameternameAndObjectAttribute(){
        String hql="from Dept dept where dname=:dname";
        Dept dd=new Dept();
        dd.setDname("RESEARCH");
        Query query=session.createQuery(hql);
        query.setProperties(dd);
        List<Dept> list=query.list();
        for(Dept dept : list){
            System.out.println(dept.getDname());
        }
    }


}

Hibernate=====HQL實用技術