Oracle数据给定默认值与相+-

Oracle数据给定默认值与相±

with a as(
select '全区' as city, 100 as "处理量数据", 80 as "积压量数据" from table_a
),
b as(
select city,nvl(处理量数据,0) - nvl(积压量数据,0) as "总数" from a
)select * from b group by city,总数