想设置当参数xs为‘24小时’时，查过去24小时数据，否则查询48小时数据，请问这个SQL应该怎么改呢？

select nature_hour, cls_name, sum(sales_num) as 销量 from ads_sales_hy where 1=1 

${if(xs="24小时","and nature_hour>='format(DATEDELTA(now(),-1),"yyyy-MM-dd H")'","and and nature_hour>='format(DATEDELTA(now(),-2),"yyyy-MM-dd H")'")} 

group by nature_hour, cls_name order by nature_hour, cls_name