SQL：Where子句

Question

SELECT DISTINCT Campaign_id 
FROM Impressions 
WHERE Date BETWEEN '2015-03-01' AND '2015-03-31' ; 

上述查詢給我的結果對於一直在積極在2015年3月1日和2015年3月31日之間的任何日期Campaign_id的。

我希望結果集包含campaign_id，如果在2015-03-01和2015-03-31之間的所有日期都處於活動狀態。

我怎麼會去嗎？

Answer 1

假設DATE是DATE數據類型並且沒有時間分量。

DECLARE @Start DATE = '2015-03-01', 
     @End DATE = '2015-03-31' 

SELECT Campaign_id 
FROM Impressions 
WHERE Date BETWEEN @Start AND @End 
GROUP BY Campaign_id 
HAVING COUNT(DISTINCT Date) = 1 + DATEDIFF(DAY, @Start, @End); 

---

或者一個版本不變量

SELECT Campaign_id 
FROM Impressions 
     CROSS APPLY (VALUES ({ d '2015-03-01' }, 
          { d '2015-03-31' })) V([Start], [End]) 
WHERE [Date] BETWEEN [Start] AND [End] 
GROUP BY Campaign_id, [Start], [End] 
HAVING COUNT(DISTINCT Date) = 1 + DATEDIFF(DAY, [Start], [End]); 

Answer 2

使用HAVING子句COUNT(DISTINCT)：

SELECT Campaign_id 
FROM Impressions 
WHERE Date between '2015-03-01' and '2015-03-31' 
GROUP BY Campaign_id 
HAVING COUNT(DISTINCT Date) = 31; 

你也應該由Aaron伯特蘭審查這一blog post理解爲什麼使用BETWEEN日期是一個壞主意。

您可以安排查詢，只能通過做類似提及的日期一次：

WITH params as (
     SELECT CAST('2015-03-01' as DATE) as date1, CAST('2015-03-31' as DATE) date2 
    ) 
SELECT i.Campaign_id 
FROM params CROSS JOIN 
    Impressions i 
WHERE i.Date >= params.Date1 and i.Date < DATEADD(day, 1, params.Date2) 
GROUP BY i.Campaign_id, params.date1, params.date2 
HAVING COUNT(DISTINCT i.Date) = 1 + DATEDIFF(day, params.date1, params.date2); 

注：有些人會喜歡JOIN到CROSS JOIN在這種情況下。按照習慣，我總是在使用CROSS JOIN的查詢中添加參數CTE。