java的oracle数据库用hql语句(orcal)对日期进行范围对比

/**取当前时间30分钟前的*/
Date date = new Date();
		long time = (date.getTime()/1000)-60*30;
		date.setTime(time*1000);
		SimpleDateFormat formatter=new SimpleDateFormat("yyyy-MM-dd HH:mm");
		String beforeDate = formatter.format(date);
		Date date1 = new Date();
/**取当前时间30分钟后的*/
		long time1 = (date1.getTime()/1000)+60*30;
		date1.setTime(time1*1000);
		String afterDate = formatter.format(date1);
/**hql语句中须对javabean取出的日期字段进行to_char，因为to_date中第一个参数是字符串,javabean取出的是日期类型*/
	 	String hql = "from OpenMeetingCourse where  to_date(to_char(beginTime, 'yyyy-mm-dd hh24:mi')," + 
		        "'yyyy-mm-dd hh24:mi') >=to_date('" + beforeDate + "','yyyy-mm-dd hh24:mi') and " + 
	 			"to_date(to_char(beginTime, 'yyyy-mm-dd hh24:mi')," + 
		        "'yyyy-mm-dd hh24:mi')<=to_date('" + 
	 			afterDate + "','yyyy-mm-dd hh24:mi') order by idCourse desc";