JPQL를 사용하여 기본 쿼리

모든 문의

    @Test
    public void testFindAll(){
        EntityManager entityManager = JpaUtils.getEntityManager();
        EntityTransaction tx = entityManager.getTransaction();
        tx.begin();
        //查询全部的步骤
        //1.创建Query查询对象，query对象才是执行jpql的对象
        String jpql = "from com.leewle.domain.Customer";
        Query query = entityManager.createQuery(jpql);
        //2.发送查询并产生结果集
        List<Customer> list = query.getResultList();
        for(Customer customer:list){
            System.out.println(customer);
        }
        entityManager.close();
    }

페이징 쿼리

    @Test
    public void testPage(){
        EntityManager entityManager = JpaUtils.getEntityManager();
        EntityTransaction tx = entityManager.getTransaction();
        tx.begin();
        //查询全部的步骤
        //1.创建Query查询对象，query对象才是执行jpql的对象
        String jpql = "from Customer";
        Query query = entityManager.createQuery(jpql);
        //对参数赋值 --- 分页参数
        //起始索引
        query.setFirstResult(0);
        //每页查询的条数
        query.setMaxResults(2);
        //2.发送查询并产生结果集
        List<Customer> list = query.getResultList();
        for(Customer customer:list){
            System.out.println(customer);
        }
        entityManager.close();
    }

조건 문의

    @Test
    public void testCondition(){
        EntityManager entityManager = JpaUtils.getEntityManager();
        EntityTransaction tx = entityManager.getTransaction();
        tx.begin();
        //查询全部的步骤
        //1.创建Query查询对象，query对象才是执行jpql的对象
        String jpql = "from Customer where custId = ?";
        Query query = entityManager.createQuery(jpql);
        //对占位符参数赋值
        //第一个参数：占位符索引位置(1 开始)
        //第二个参数：取值
        query.setParameter(1,1l);
        //执行query
        Customer customer = (Customer) query.getSingleResult();
        System.out.println(customer);
        entityManager.close();
    }

정렬 쿼리

    @Test
    public void testFindAllDesc(){
        EntityManager entityManager = JpaUtils.getEntityManager();
        EntityTransaction tx = entityManager.getTransaction();
        tx.begin();
        //查询全部的步骤
        //1.创建Query查询对象，query对象才是执行jpql的对象
        String jpql = "from com.leewle.domain.Customer order by custId DESC";
        Query query = entityManager.createQuery(jpql);
        //2.发送查询并产生结果集
        List<Customer> list = query.getResultList();
        for(Customer customer:list){
            System.out.println(customer);
        }
        entityManager.close();
    }

통계 조회

    @Test
    public void testCount(){
        EntityManager entityManager = JpaUtils.getEntityManager();
        EntityTransaction tx = entityManager.getTransaction();
        tx.begin();
        //查询全部的步骤
        //1.创建Query查询对象，query对象才是执行jpql的对象
        String jpql = "select count(custId) from Customer";
        Query query = entityManager.createQuery(jpql);
        //2.发送查询并产生结果集
        Long count = (Long) query.getSingleResult();
        System.out.println(count);
        entityManager.close();
    }