问一个Hibernate与SQL的问题！在Hibernate里调用sql语句，语句用了SQL的自定义函数

CREATE   FUNCTION   f_ConcatPartys(@org numeric,@date_from datetime,@date_to datetime) 

RETURNS   VARCHAR(8000) 

AS   

BEGIN 

declare   @sql   varchar(8000) 

set   @sql= '' 

select   @sql=isnull(@sql+'、','')+t_name from [Table] where org_id = @org_id and date_f >= @date_from and date_t <= @date_to order by id

RETURN   @sql

END

HQuery hquery=new HQuery();

String hsql="dbo.f_ConcatPartys("+org_id+",'"+date_from+"','"+date_to+"') from [Table] as a where a.date_f >='"+date_from+"' and a.date_t <= '"+date_to+"' and group by a.org_id";

hquery.setQueryString(hsql);

List _list=this.find(hquery);



报错：

net.sf.hibernate.QueryException: undefined alias: f_ConcatPartys [select dbo.f_ConcatPartys(98336778,'20080101','20080101') from ....