嘗試子查詢時出現 Ambiguous column name 錯誤

Question

提示為假設風險為“1”的設施每年至少需要進行 3 次檢查。 顯示 2013 年未能滿足此要求且至少有 1 次未通過 Canvass 類型檢查的設施。顯示設施名稱以及它在 2013 年進行的 Canvass 檢查次數。提示：使用子查詢

所以這是我的代碼

SELECT DBAName, COUNT(*)
FROM FoodInspectionOriginal, Organization
WHERE Risk = 1 AND [Inspection Type] IN (SELECT [Inspection Type] FROM FoodInspectionOriginal WHERE [Inspection Type] = 'Canvass' AND [Inspection Date] = Year(2013))
GROUP BY DBAName;

我得到這是輸出

Msg 209, Level 16, State 1, Line 3

不明確的列名稱“風險”。

Answer 1

我只會使用聚合。 假設 table foodinspectionoriginal表結構foodinspectionoriginal ：

dbaname           -- name of the facility
inspection_date   
inspection_type   -- "Canvass", ...
inspection_status -- "successful", "failed"

查詢可以表述如下：

select dbaname,
    sum(case when inspection_type = 'Canvass' and inspection_status = 'failed' then 1 else 0 end) as cnt_failed_canvass
from foodinspectionoriginal
where 
    risk = 1 
    and inspection_date >= '20130101' 
    and inspection_date <  '20140101'
group by dbaname 
having 
    count(*) < 3 
    and sum(case when inspection_type = 'Canvass' and inspection_status = 'failed' then 1 else 0 end) > 0