SQL: Where Clause - sql

Question

SELECT DISTINCT Campaign_id
FROM Impressions
WHERE Date BETWEEN '2015-03-01' AND '2015-03-31' ;
The above query gives me the result for the Campaign_id's that have been active on any date between 2015-03-01 and 2015-03-31.
I want the result set to contain the campaign_id's if the have been active on all the dates in between 2015-03-01 and 2015-03-31.
How would I go about this?

Answer 1

Assuming DATE is a DATE datatype and has no time component.
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);
Or a version without the variables
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

Using HAVING clause with 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;
You should also review this blog post by Aaron Betrand to understand why using BETWEEN for dates is a bad idea.
You can make arrange the query to only mention the dates once by doing something like:
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);
Note: Some would prefer a JOIN to a CROSS JOIN in this case. By habit, I always put a parameters CTE in a query using CROSS JOIN.