Question

In TSQL, how can I can get the previous hour snapping to the hour.

So for example, if it was now 2:33, how would I get fields where CreationDate (a datetime field) is greater than or equal to 1:00 and less than 2:00.

I would also like to to do this with 10 minute intervals (snapping to the previous :00 – :10 if it were currently :14 for example, or another example, :50-:00 if it were :06).

Answer 1

This would get you the start and end of the current hour:

select  dateadd(hour, datepart(hour, getdate()), 
            dateadd(day, 0, datediff(day, 0, getdate())))
,       dateadd(hour, 1+datepart(hour, getdate()), 
            dateadd(day, 0, datediff(day, 0, getdate())))

Explanation: dateadd(day, 0, datediff(day, 0, getdate())) gets you the start of today. Then you add the current hour to that.

Along the same lines for the previous 10 minute block:

select  dateadd(minute, datepart(minute, getdate()) / 10 * 10 - 10, 
            dateadd(hour, datepart(hour, getdate()), 
                dateadd(day, 0, datediff(day, 0, getdate()))))
,       dateadd(minute, datepart(minute, getdate()) / 10 * 10, 
            dateadd(hour, datepart(hour, getdate()), 
                dateadd(day, 0, datediff(day, 0, getdate()))))

Or another way of writing it:

declare @lowerBound datetime = dateadd(minute, datepart(minute, getdate()) / 10 * 10 - 10, 
            dateadd(hour, datepart(hour, getdate()), 
                dateadd(day, 0, datediff(day, 0, getdate()))))

declare @upperBound datetime = dateadd(minute, datepart(minute, getdate()) / 10 * 10, 
            dateadd(hour, datepart(hour, getdate()), 
                dateadd(day, 0, datediff(day, 0, getdate()))))

select @lowerBound, @upperBound

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