select distinct 品类,sum(aexp_w+aexp_n)/10000 as '加税合计' from V_LUJJ_SAL_mt
where 1=1
and 月份 = replace('${ny}','-','')
${if(len(zzmc) == 0,"","and 组织简称  = '" + zzmc + "'")}
${if(len(pl) == 0,"","and 品类  = '" + pl + "'")}
${if(len(dq) == 0||dq = "中国","","and 省 = '" + dq + "'")}
${if(len(dq) == 0||dq = "中国","","and 城市 = '" + dq + "'")}
${if(len(dq) == 0||dq = "中国","","and 区县 = '" + dq + "'")}
group by 品类

如何写这个where条件，根据参数dq不同，显示各层级（中国，省，城市，区县）的数据？