用料统计SQL

有个计划表1， 记录物料的年度计划量
有个实际使用情况表2，记录实际使用情况。
最后要出个统计表，把计划和实际的数据结合到一起进行统计，
有特殊的情况就是可能部分物料有计划但是没有实际使用，有的物料无计划但是有实际使用情况，
要把这些数据合并到一起按照季度进行统计并算差异量，能实现吗？？

create table plan(OBJ varchar2(10),YEAR number(4),PLAN_COUNT number(10));
create table actual(OBJ varchar2(10),YEAR number(4),SEASON number(10),USED number(10));

with t1 as (
select distinct a.obj,p.plan_count,a.year,
case when a.season=1 then sum(a.used) over (partition by a.obj,a.season) else null end as s1,
case when a.season=2 then sum(a.used) over (partition by a.obj,a.season) else null end as s2,
case when a.season=3 then sum(a.used) over (partition by a.obj,a.season) else null end as s3,
case when a.season=4 then sum(a.used) over (partition by a.obj,a.season) else null end as s4,
sum(a.used) over (partition by a.obj) as sum_count 
from actual a left join plan p on a.obj=p.obj order by 1,4
)
select temp.obj,nvl(temp.plan_count,0),temp.year,temp.q1,temp.q2,temp.q3,temp.q4,nvl(temp.sum_count,0),(nvl(temp.plan_count,0)-nvl(temp.sum_count,0)) as diff 
from(
select distinct t1.obj,t1.plan_count,t1.year,
sum(s1) over (partition by t1.obj) as Q1,
sum(s2) over (partition by t1.obj) as Q2,
sum(s3) over (partition by t1.obj) as Q3,
sum(s4) over (partition by t1.obj) as Q4,t1.sum_count from t1
union all
select pl.obj,pl.plan_count,pl.year,null,null,null,null,null from plan pl where pl.obj not in (select distinct obj from actual)
) temp 
order by 1