問題與連接在我的查詢，如何填充空值爲零

Question

我的查詢是獲取過去5周的數據。

select z.week, 
sum(case when i.severity=1 then 1 else 0 end) as 1 
sum(case when i.severity=2 then 1 else 0 end) as 2 
sum(case when i.severity=3 then 1 else 0 end) as 3 
sum(case when i.severity=4 then 1 else 0 end) as 4 
from instance as i 
and left outer join year as z on convert(varchar(10),z.date,101)=convert(varchar(10),i.created,101) 
and left outer join year as z on convert(varchar(10),z.date,101)=convert(varchar(10),i.closed,101) 
where i.group in '%Teams%' 
and z.year=2013 
and z.week<=6 and z.week>1 

這裏有幾個星期在我的實例表中，甚至沒有一行。所以這裏我沒有得到空或零...而是整個行並沒有提示。

我目前的輸出。

week | 1 | 2 | 3 | 4 
--------------------- 
2 | 0 | 1 | 8 | 5 
3 | 2 | 3 | 4 | 9 
5 | 1 | 0 | 0 | 0 

，但我需要像下面的輸出...

week | 1 | 2 | 3 | 4 
--------------------- 
2 | 0 | 1 | 8 | 5 
3 | 2 | 3 | 4 | 9 
4 | 0 | 0 | 0 | 0 
5 | 1 | 0 | 0 | 0 
6 | 0 | 0 | 0 | 0 

如何獲得所需的outputiñSQL

Answer 1

試試這個

select z.week, 
sum(case when i.severity=1 then 1 else 0 end) as 1 
sum(case when i.severity=2 then 1 else 0 end) as 2 
sum(case when i.severity=3 then 1 else 0 end) as 3 
sum(case when i.severity=4 then 1 else 0 end) as 4 
from year as z 
left outer join instance as i on 
convert(varchar(10),z.date,101)=convert(varchar(10),i.created,101) 
and convert(varchar(10),z.date,101)=convert(varchar(10),i.closed,101) 
where (i.group is null or i.group in '%Teams%') 
and z.year=2013 
and z.week<=6 and z.week>1 

Answer 2

我不知道查詢是如何工作的，您在別名year兩次到z。但是，假設這不是問題，您可以將LEFT OUTER JOIN更改爲RIGHT OUTER JOIN。或者，如果您不喜歡RIGHT OUTER JOIN，請重新選擇SELECT，以便FROM子句引用year表。