如何返回varchar字符串而不是null與彙總？

Question

當我運行此查詢：

select 
    First_Name, 
    sum(a) a, 
    sum(b) b, 
    sum(c) c 
from someTable 
group by First_Name with rollup 

第一列First_Name和最後一行（總行）是NULL（因爲它不能概括），我想顯示自定義字符串值，而不是空值。我知道我可以在這裏使用isnull或case，但我只想要捲起的行受到影響。

謝謝！

Answer 1

SELECT CASE WHEN GROUPING_ID(First_Name) = 1 THEN 'Total' ELSE First_Name END, 
     SUM(a), 
     SUM(b), 
     SUM(c) 
FROM data 
GROUP BY 
     First_Name WITH ROLLUP 

Answer 2

CASE WHEN GROUPING(First_Name) = 1 THEN 'FOO' ELSE First_Name END AS First_Name