HQL 语句的执行

HQL(Hibernate Query Language)
面向对象的查询语言,与sql不同，hql中的对象名是区分大小写的（除了java和属性其它部分不区分大小写）；hql中查的是对象而不是表，并且支持多态；hql主要通过Query来操作。
使用步骤：
1获取session对象
2.编写HQL语句
3.创建Query对象
4.执行查询，得到查询结果



package cn.text.java.cn.happy.test;
import cn.happy.entity.Dept;
import cn.happy.entity.Dog;
import cn.hql.entity.demp;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.junit.Test;
import java.util.List;
/**
 * Created by Happy on 2017-09-18.
 * 勿忘国耻  为中华之崛起而读书
 */
public class Test20170920 {
    @Test
    public void testdel(){
        //Configuration
        Configuration cfg=new Configuration().configure();//1
        //session对象
        SessionFactory factory=cfg.buildSessionFactory(); //2
        Session session = factory.openSession(); //3
        Transaction tx = session.beginTransaction();//4
        Dog dog=new Dog();
        dog.setDogid(2);
        session.delete(dog);
        tx.commit();//5
        System.out.println("deleate ok!");
        session.close();
    }
    @Test
    public void loadtext() {
        Configuration cfg = new Configuration().configure();//1
        //session对象
        SessionFactory factory = cfg.buildSessionFactory(); //2
        Session session = factory.openSession(); //3
        Transaction tx = session.beginTransaction();//4
        String hql = "from demp";
        Query query = session.createQuery(hql);
        List<demp> list = query.list();
        for (demp depts : list) {
            System.out.println(depts.getDempname());

        }
    }
    //02.案例：我想检索 名称为"开发部" 部门集合
    @Test
    public void selectSomeRecordsFromTable(){
        //你找方案
        Configuration cfg = new Configuration().configure();//1
        //session对象
        SessionFactory factory = cfg.buildSessionFactory(); //2
        Session session = factory.openSession(); //3
        Transaction tx = session.beginTransaction();//4
        String hql="from demp demp where demp.dempname='财务部'";
        Query query = session.createQuery(hql);
        List<demp> list = query.list();
        for (demp dept:list){
            System.out.println(dept.getDempname());
        }

    }
    //02.案例：参数查询 ：方案一：？匿名占位符
    @Test
    public void selectByConditionNiming(){
        Configuration cfg = new Configuration().configure();//1
        //session对象
        SessionFactory factory = cfg.buildSessionFactory(); //2
        Session session = factory.openSession(); //3
        Transaction tx = session.beginTransaction();//4
        String hql="from demp where dempname=?";//为？号赋值
        Query query = session.createQuery(hql); //q.setString(0,name);//下标从0开始，对应设置“？”的参数
        query.setParameter(0,"45");
        List<demp> list = query.list();
        for (demp dept1:list){
            System.out.println(dept1.getDempname());
        }
    }

    //02.案例：参数查询 ：方案二：:name  参数名称绑定
    //    使用“：起个名字”   表示未知量，然后是对这个“起个名字赋值”

    @Test
    public void selectByConditionParametername(){
        Configuration cfg = new Configuration().configure();//1
        //session对象
        SessionFactory factory = cfg.buildSessionFactory(); //2
        Session session = factory.openSession(); //3
        Transaction tx = session.beginTransaction();//4
        String hql="from demp where dempname=:dempname";
        Query query = session.createQuery(hql);
        query.setParameter("dempname","2");
        List<demp> list = query.list();
        for (demp depts:list){
            System.out.println(depts.getDempname());
        }
    }
    //02.案例：参数查询 ：方案三：:name  参数名称绑定++++对象属性
    @Test
    public void selectByConditionParameternameAndObjectAttribute(){
        Configuration cfg = new Configuration().configure();//1
        //session对象
        SessionFactory factory = cfg.buildSessionFactory(); //2
        Session session = factory.openSession(); //3
        Transaction tx = session.beginTransaction();//4
        String hql="from demp where dempname=:dempname";
        demp dd=new demp();
        dd.setDempname("开发部");
        Query query = session.createQuery(hql);
        query.setProperties(dd);
        List<demp> list = query.list();
        for (demp dept2:list){
            System.out.println(dept2.getDempname());
        }
    }

}