數查詢如果WHERE條件匹配，則表明計否則爲零

Question

我有兩個表

1.stages 
Sr No Stages 
2 A 
7 B 
12 C 
17 D 
22 E 
27 F 
2.salesdetiail 
Stage Sale Product 
A 2 xyz 
B 1 Yzw 

我想導致

Stages Sum(sale) 
A 2 
B 1 
C 0 
D 0 
E 0 
F 0 

我嘗試了所有可能的解決方案，但任何人都failed.Can幫我解決這個

Answer 1

您可以嘗試像下面使用LEFT JOIN

select s.stages, 
case when sd.sale is not null then sd.sale else 0 end as sale 
from stages s left join salesdetail sd on s.stages = sd.stages; 

Answer 2

試試下面的query

SELECT s.stages, SUM(IF sd.sale IS NULL,0,sd.sale) AS sale 
FROM stages s LEFT JOIN salesdetail sd ON s.stages = sd.stages 
Group by s.stages; 

Answer 3

試試這個

select s.stages, 
SUM(case when sd.sale is not null then sd.sale else 0 end) as sale 
from stages s left join salesdetail sd on s.stages = sd.stages 
group by s.stages; 

希望它可以解決你的問題