Hibernate count如何映射？HQL别名字段问题？

问：hibernate， select name, count(*) from table group by name。这句话应该怎么用HQL语句执行？或者在hibernate中该怎么查出每个name对应的count？

 

答：String hql = "select name, count(*) from table group by name";   //跟sql语句差不多的，不过这里的name是类的属性，table 是类名，因为HQL是面向对象的查询的语言。

首先要获得session，你懂的，
然后  Query query = session.createQuery(hql);
List list = query.list();
获取list里面的name ：
Iterator it = lits.iterator();
if(it.hasNext()){
    Object[]  obj = (Object[]) it.next();
    String name = obj[0];
    int count = obj[1];
}

 

在项目开发中的具体情况：

//关键是处理count映射问题。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();	 
	            
	            //封装
	            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++;
	            }

 

说明：HQL别名字段

hibernate执行时打印出HQL
<property name="show_sql">true</property>

Hibernate: select bbscslogin0_.UserID as col_0_0_, bbscslogin0_.NickName as col_1_0_, count(bbscslogin0_.ID) as col_2_0_ from bbscs6.bbscs_logintimes bbscslogin0_ where LoginYear=? and LoginMonth=? group by bbscslogin0_.UserID order by col_2_0_ desc limit ?

UserID别名 ~ col_0_0_
NickName别名 ~ col_1_0_
count(bbscslogin0_.ID)别名 ~ col_2_0_

所以上面的HQL语句：group by userId order by col_2_0_ desc  //按count统计量来降序排列。

 

 

 

 

 

 

 

 

 

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