Hibernate count映射問題

原創

2020-02-21 12:06

問：hibernate， select name, count(*) from table group by name。這句話應該怎麼用HQL語句執行？或者在hibernate中該怎麼查出每個name對應的count？

答：String hql = "select name, count(*) from table group by name"; //跟sql語句差不多的，不過這裏的name是類的屬性，table 是類名，因爲HQL是面向對象的查詢的語言。

首先要獲得session，你懂的，
然後 Query query = session.createQuery(hql);
List list = query.list();
獲取list裏面的name ：
Iterator it = lits.iterator();
if(it.hasNext()){
    Object[] obj = (Object[]) it.next();
    String name = obj[0];
    int count = obj[1];
}

在項目開發中的具體情況：

//關鍵是處理count映射問題。120221 hjl  
                String q = "select userId, nickName, count(id)  from BbscsLogintimes  where LoginYear = ? and LoginMonth = ?  group by userId order by col_2_0_ desc";  
     
                Query query = session.createQuery(q);  
                query.setLong(0, Long.valueOf(year));  
                query.setLong(1, Long.valueOf(mon));    
                List list = query.list();      
                  
                //封裝  
                List list2 = new ArrayList();  
                BbscsLogintimes logintimes= null;  
                Iterator it = list.iterator();  
                long j = 1;  
                while(it.hasNext()){  
                    logintimes = new BbscsLogintimes();  
                    Object[]  obj = (Object[]) it.next();  
                    logintimes.setOrderId(j);  
                    logintimes.setOrderName((String) obj[1]);  
                    logintimes.setOrderNum((Integer)obj[2]);  
                    list2.add(logintimes);  
                    j++;  
                }

以上轉載自：http://simpledev.iteye.com/blog/1433282

此爲本人項目中的具體代碼：（***DaoImpl.java）

需求：查詢出 ××人（字段：userId）購買了 ×× （字段：number）注幸運碼

@Override
    public List<UserLottery> listUserLotteryQuantity(int drawNum) {
       Query query =  entityManager.createNativeQuery("SELECT ul.user_id, count(ul.user_id) AS numQuantity FROM user_lottery_history ul WHERE ul.draw_num =:drawNum GROUP BY ul.user_id ORDER BY ul.user_lottery_history_id DESC LIMIT 10")
               .setParameter("drawNum", drawNum);
       List list = query.getResultList();
       List<UserLottery> ulList = new ArrayList<UserLottery>();
       UserLottery ul = null;
       User user = null;
       Iterator it = list.iterator(); 
       while(it.hasNext()) {
           Object[]  obj = (Object[]) it.next();  
           ul = new UserLottery();
           user = new User();
           user.setUserId(((BigInteger) obj[0]).longValue());
           ul.setUser(user);
           ul.setNumber(obj[1].toString());
           ulList.add(ul);
       }
       return ulList;
    }