如同b是a的明细 c是b的明细
三句sql分别为 select a ,b,c , sum(d) from 1 group by a
select a ,b,c , sum(d) from 1 group by a ,b
select a ,b,c , sum(d) from 1 group by a ,b ,c
条件属性实现折叠树-https://help.fanruan.com/finereport/doc-view-3276.html