sql - 在底部添加总计

Question

我需要在表格底部添加一个总计。这在我的场景中可能吗？

select country, count(*) from customer
group by country

Country         Count
  USA              5  
  UK              10
 Canada           15 
 Russia           25
                  55  (Requested from SO community) 

Answer 1

使用rollup()

select country, count(*) 
from customer
group by rollup (country )

如果你还想要标签“Total”，你可以使用grouping函数:

select case 
          when grouping(country) = 1 then 'Total' 
          else country 
       end as country, 
       count(*) 
from customer
group by rollup (country )

在线示例:http://rextester.com/PKFE63954