HQL 語句的執行

HQL(Hibernate Query Language)
面向對象的查詢語言,與sql不同，hql中的對象名是區分大小寫的（除了java和屬性其它部分不區分大小寫）；hql中查的是對象而不是表，並且支持多態；hql主要通過Query來操作。
使用步驟：
1獲取session對象
2.編寫HQL語句
3.創建Query對象
4.執行查詢，得到查詢結果



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.
 * 勿忘國恥  為中華之崛起而讀書
 */
public class Test20170920 {
    @Test
    public void testdel(){
        //Configuration
        Configuration cfg=new Configuration().configure();//1
        //session對象
        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對象
        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：我想檢索 名稱為"開發部" 部門集合
    @Test
    public void selectSomeRecordsFromTable(){
        //你找方案
        Configuration cfg = new Configuration().configure();//1
        //session對象
        SessionFactory factory = cfg.buildSessionFactory(); //2
        Session session = factory.openSession(); //3
        Transaction tx = session.beginTransaction();//4
        String hql="from demp demp where demp.dempname='財務部'";
        Query query = session.createQuery(hql);
        List<demp> list = query.list();
        for (demp dept:list){
            System.out.println(dept.getDempname());
        }

    }
    //02.案例：參數查詢 ：方案一：？匿名占位符
    @Test
    public void selectByConditionNiming(){
        Configuration cfg = new Configuration().configure();//1
        //session對象
        SessionFactory factory = cfg.buildSessionFactory(); //2
        Session session = factory.openSession(); //3
        Transaction tx = session.beginTransaction();//4
        String hql="from demp where dempname=?";//為？號賦值
        Query query = session.createQuery(hql); //q.setString(0,name);//下標從0開始，對應設置“？”的參數
        query.setParameter(0,"45");
        List<demp> list = query.list();
        for (demp dept1:list){
            System.out.println(dept1.getDempname());
        }
    }

    //02.案例：參數查詢 ：方案二：:name  參數名稱綁定
    //    使用“：起個名字”   表示未知量，然后是對這個“起個名字賦值”

    @Test
    public void selectByConditionParametername(){
        Configuration cfg = new Configuration().configure();//1
        //session對象
        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：參數查詢 ：方案三：:name  參數名稱綁定++++對象屬性
    @Test
    public void selectByConditionParameternameAndObjectAttribute(){
        Configuration cfg = new Configuration().configure();//1
        //session對象
        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("開發部");
        Query query = session.createQuery(hql);
        query.setProperties(dd);
        List<demp> list = query.list();
        for (demp dept2:list){
            System.out.println(dept2.getDempname());
        }
    }

}