这个hibernate分组查询怎么写

0 0

这个hibernate分组查询怎么写5

表StationData如下：
id | station_id | speed | direction | temperature | rainfall |   X   |   Y   |     create_time
1 |      1     | 12.000 |   20.200 |    23.000   |   1.000 | 2.000 | 0.000 | 2008-07-03 00:00:00
2 |      2     | 15.000 |   16.000 |    22.000   |   2.000 | 2.000 | 0.000 | 2008-07-03 02:05:00
3 |      1     | 14.000 |   13.800 |    13.000   |   2.000 | 2.000 | 3.000 | 2008-07-03 01:00:00
4 |      2     | 15.000 |   26.000 |    22.800   |   5.000 | 3.000 | 4.000 | 2008-07-03 00:00:00

对于表StationData，需要按照station_id来分组查询，根据create_time每次查询出每个station下的最新纪录。根据本表，希望最终得到的查询数据为：
id | station_id | speed | direction | temperature | rainfall |   X   |   Y   |     create_time
3 |      1     | 14.000 |   13.800 |    13.000   |   2.000 | 2.000 | 3.000 | 2008-07-03 01:00:00
2 |      2     | 15.000 |   16.000 |    22.000   |   2.000 | 2.000 | 0.000 | 2008-07-03 02:05:00

不知道HQL该怎么写，目前我的写法如下，但是不对，还请大家指教。


public List findStationByMaxTime() {
	try {
		String queryString = "from StationData as model group by stationId order by createTime desc ";
		Query queryObject = getSession().createQuery(queryString);
		queryObject.setFirstResult(0);
		queryObject.setMaxResults(10);
		return queryObject.list();
	} catch (RuntimeException re) {
		log.error("find by property name failed", re);
		throw re;
	}
}

Hibernate

2008年7月03日 04:57

redlly
45
0 0 0

1个答案按时间排序按投票排序

0 0

由于你只给出了表结构，所以建议使用本地sql实现：
这是SQL

select {a.*} from StationData a group by a.station_id having max(create_time)

java码：

public List findStationByMaxTime() {
	try {
		String queryString = "select {a.*} from StationData a group by a.station_id having max(create_time)";
		Query queryObject = getSession().createSQLQuery(queryString);
		return queryObject.list();
	} catch (RuntimeException re) {
		log.error("find by property name failed", re);
		throw re;
	}
}

2008年7月03日 10:30