hibernateHQL语句

一、hql

1. 什么是hql
HQL是Hibernate Query Language的缩写

查全部

2. hql和sql区别/异同
HQL SQL
类名/属性 表名/列名
区分大小写,关键字不区分大小写 不区分大小写
别名 别名
?，从下标0开始计算位置(hibernate5之后不支持) ?，从顺序1开始计算位置
:命名参数 不支持:命名参数
面向对象的查询语言 面向结构查询语言

hqlTest

public class HqlTest {

    Session session=null;
    Transaction trans=null;
    BookDao bookDao=new BookDao();

//    @Before
//    public void setUp() {
//        session=SessionFactoryUtils.openSession();
//        trans=session.beginTransaction();
//    }
//
//    @After
//    public void tearDown() {
//        trans.commit();
//        SessionFactoryUtils.closeSession();
//    }

    @SuppressWarnings("deprecation")

    @Test
    public  void test() {
        String hql="";
        //一.HQL
        //1.HQL之查询返回List<T>
//         hql="from Book";
//        Query<Book> createQuery = session.createQuery(hql, Book.class);
//        List<Book> list = createQuery.list();
//        for (Book book : list) {
//            System.out.println(book);
//        }

        //2.HQL之查询返回单个属性
//        hql="select b.bookName from Book b";
//        Query query = session.createQuery(hql);
//        List list = query.list();
//        for (Object object : list) {
//            System.out.println(object);
//        }
        //3.HQL之查询返回多个属性
//        hql="select bookId,bookName from Book";
//        Query createQuery = session.createQuery(hql);
//        List list = createQuery.list();
//        for (Object object : list) {
//            //Object==object[]
//            System.out.println(Arrays.toString((Object[])object));
//        }
        //4.HQL之new Map
//        hql="select new Map(b.bookId as bid, b.bookName as bname) from Book b";
//        Query query = session.createQuery(hql);
//        List<Map<String, Object>> list = query.list();
//        for (Map<String, Object> map : list) {
//            System.out.println(map);
//        }

//        5.HQL之new 构造方法
//        hql="select new Book(b.bookId,b.bookName,b.price) from Book b ";
//        Query createQuery = session.createQuery(hql);
//        List list = createQuery.list();
//        for (Object object : list) {
//            System.out.println(object);
//        }
//        6.HQL之命名参数
        //hql="from Book where price>:min and price<:max";
//        hql="from Book where bookId in (:ids)";
//        Query<Book> query = session.createQuery(hql, Book.class);
//        query.setParameter("min", 40f);
//        query.setParameter("max", 1000f);
//        query.setParameterList("ids",new Integer[] {1,2,3});
//        List<Book> list = query.list();
//        for (Book book : list) {
//            System.out.println(book);
//        }

        //7.HQL之聚合函数(count/sum/avg/min/max)
//        hql="select sum(b.price) as total from Book b";
//        Query createQuery = session.createQuery(hql);
//        List list = createQuery.list();
//        for (Object object : list) {
//            System.out.println(object);
//        }
//        8.HQL之连接查询
//        hql="select b.bookId,b.bookName,b.price"
//                + ",c.categoryId,c.categoryName from Book b inner join "
//                + "b.categroies c";
//        Query query = session.createQuery(hql);
//        List list = query.list();
//        for (Object object : list) {
//            System.out.println(Arrays.toString((Object[])object));
//        }
        //        9.HQL之分页查询
//        int page=1;
//        int rows=2;
//
//        hql="from Book";
//        Query<Book> query = session.createQuery(hql, Book.class);
//        query.setFirstResult((page-1)* rows);
//        query.setMaxResults(rows);
//        List<Book> list = query.list();
//        for (Book book : list) {
//            System.out.println(book);
//        }

        //二.原生sql
        //1.原生sql查询返回Object[]
        String sql="";
//         sql="select book_id,book_name,price from t_book_hb";
//        NativeQuery query = session.createNativeQuery(sql);
//        List list = query.list();
//        for (Object object : list) {
//            System.out.println(Arrays.toString((Object[])object));
//        }

        //2.原生sql返回list<T>
//        sql="select book_id,book_name,price from t_book_hb";
//         NativeQuery<Book> query = session.createNativeQuery(sql, Book.class);
//        List<Book> list = query.list();
//        for (Book book : list) {
//            System.out.println(book);
//        }

        //3.原生sql查询返回单个属性
//        sql="select book_name from t_book_hb";
//        NativeQuery query = session.createNativeQuery(sql);
//        List list = query.list();
//        for (Object object : list) {
//            System.out.println(object);
//        }

        //4.原生sql查询返回List<Map>,适用于多表联查返回结果
        sql="SELECT *  FROM t_book_hb b,t_book_category_hb bc,t_category_hb c\r\n" +
                "WHERE b.`book_id`=bc.`bid` AND bc.`cid`=c.`category_id`";
        NativeQuery query = session.createNativeQuery(sql);

        //将结果集转换为Map集合
        query.setResultTransformer(CriteriaSpecification.ALIAS_TO_ENTITY_MAP);
        List<Map<String,Object>> list= query.list();
        for (Map<String,Object> map : list) {
        System.out.println(map);
    }

    }
    

BaseDao

    public Session getSession() {
        return SessionFactoryUtils.openSession();
    }

    /**
     * 设置Query的查询参数
     * @param params
     * @param query
     * @return
     */
    public void setParamters(Map<String,Object> params,Query query) {
        if(null==params||0==params.size())
            return;

        Set<Entry<String, Object>> set = params.entrySet();
        String name=null;
        Object value=null;
        for (Entry<String, Object> entry : set) {
            name=entry.getKey();
            value=entry.getValue();
            //判断参数是否是Collection，一般用于List/Set集合参数时使用
            if(value instanceof Collection)
                query.setParameterList(name, (Collection)value);
            //判断参数是否是Object[]
            else if(value instanceof Object[])
                query.setParameterList(name, (Object[])value);
            else
                query.setParameter(name, value);
        }
    }

    /**
     * 将普通hql语句转换成查询总记录数的hql语句
     * @param hql
     * @return
     */
    public String countSql(String hql) {
        //from Book
        //select * from Book
        int start=hql.toUpperCase().indexOf("FROM");
        return "select count(1) "+hql.substring(start);
    }

    /**
     * 查询(支持分页)
     * @param hql       普通hql语句
     * @param params    请求参数
     * @param pageBean  分页对象
     * @return
     */
    @SuppressWarnings("rawtypes")
    public List executeQuery(String hql,Map<String,Object> params,PageBean pageBean) {
        Session session=getSession();
        Query query=null;
        //1.根据满足条件查询总记录数
        if(null!=pageBean&&pageBean.isPagination()) {
            //select count(1) from Book where
            String countHql=this.countSql(hql);
            query = session.createQuery(countHql);
            this.setParamters(params, query);
        }
        query=session.createQuery(hql);
        //2.根据满足条件查询分页记录
        if(null!=pageBean&&pageBean.isPagination()) {
            query.setFirstResult(pageBean.getStartIndex());
            query.setMaxResults(pageBean.getRows());
        }
        this.setParamters(params, query);
        return query.list();
    }

BookDao

public class BookDao extends BaseDao{

    public void addBook(Book book) {
        Session session = SessionFactoryUtils.openSession();
        Transaction transaction = session.beginTransaction();
        //保存
        session.save(book);
        transaction.commit();
        SessionFactoryUtils.closeSession();
    }

    public Book get(Book book) {
        Session session = SessionFactoryUtils.openSession();
        Transaction transaction = session.beginTransaction();
        //保存
        Book b = session.get(Book.class, book.getBookId());
        if(b!=null) {
            Hibernate.initialize(b.getCategroies());
        }
        transaction.commit();
        SessionFactoryUtils.closeSession();
        return b;
    }

    //被控方
    public void delBook(Book book) {
        Session session = SessionFactoryUtils.openSession();
        Transaction transaction = session.beginTransaction();
        Book b = session.get(Book.class, book.getBookId());
        if(null!=b) {
            //解除关联关系
            Set<Category> categroies = b.getCategroies();
            for (Category category : categroies) {
                b.getCategroies().remove(category);
            }
            session.delete(b);
        }

        transaction.commit();
        SessionFactoryUtils.closeSession();

    }

/***************************通用查询***************************/

    public List<Book> list1(Book book,PageBean pageBean) {
        Session session = SessionFactoryUtils.openSession();
        Transaction transaction = session.beginTransaction();

        //下面代码处理的是book实体类的条件查询
        String bookName= book.getBookName();

        //sql语句where后面可以直接写true，而hql不能出现true
        String hql= "from Book where 1=1";
        if(StringUtils.isNotBlank(bookName)) {
            hql +=" and bookName like :bookName";
        }
        Query query=session.createQuery(hql);
        if(StringUtils.isNotBlank(bookName)) {
            query.setParameter("bookName",bookName);
        }

        //处理的是分页
        if(pageBean !=null && pageBean.isPagination()) {
             query.setFirstResult(pageBean.getStartIndex());
             query.setMaxResults(pageBean.getRows());
        }
         List list = query.list();

        transaction.commit();
        session.close();
        return list;

}

    public List<Book> list2(Book book, PageBean pageBean) {
        Session session = SessionFactoryUtils.openSession();
        Transaction transaction = session.beginTransaction();

//        下面的代码处理的是book实体类的条件查询
        String bookName = book.getBookName();
        Map<String , Object> map = new HashMap<String, Object>();
//        sql语句where后面可以直接写true，而hql语句不能出现true
        String hql = "from Book where 1=1";
        if(StringUtils.isNotBlank(bookName)) {
            hql += " and bookName like :bookName";
            map.put("bookName", bookName);
        }
        List list = super.executeQuery(hql, map, pageBean);

        transaction.commit();
        session.close();
        return list;
    }
}

测试

@Test
    public void testList1() {
        Book book = new Book();
//        book.setBookName("T226");
        PageBean pageBean = new PageBean();
        pageBean.setPage(2);
        List<Book> list1 = this.bookDao.list1(book, pageBean);
        for (Book b : list1) {
            System.out.println(b);
        }
    }

@Test
    public void testList2() {
        Book book = new Book();
        book.setBookName("%西游记%");
        PageBean pageBean = new PageBean();
//        pageBean.setPage(2);
        List<Book> list1 = bookDao.list2(book, pageBean);
        for (Book b : list1) {
            System.out.println(b);
        }
    }