Find first day of year first day of month etc you can use the following code declare date datetime.
T sql floor date time in 5 minute window.
Sql server all supported versions azure sql database azure sql managed instance azure synapse analytics parallel data warehouse this function returns an integer representing the specified datepart of the specified date.
See date and time data types and functions transact sql for an overview of all.
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Though i have written more than 2300 blog posts i always find things which i have not covered earlier in this blog post.
There s a couple reasons why i don t go that route.
Sql server all supported versions azure sql database azure sql managed instance azure synapse analytics parallel data warehouse returns the largest integer less than or equal to the specified numeric expression.
It only works on rounding up or down to the nearest day.
For example using the lag function is so much better than doing a self join.
T sql window functions make writing many queries easier and they often provide better performance as well over older techniques.
5 minute intervals and use that in the group by.
Floor a datetime in sql server suppose you are given a datetime and want to emulate the floor function on it eg.
This convert the period to date time format select note the 5 the minute and the starting point to convert the period back to original time dateadd minute ap fiveminutesperiod 5 2010 01 01t00 00 00 as period ap avgvalue from this groups by the period and gets the average select p fiveminutesperiod avg p value as.
Well not earlier but it is here today about how to create a function to round up time to nearest minute interval.
In the select add 5 times the number of 5 minute intervals back to the fix date to get the start of the 5 minute period.
To get better performance overall however you need to understand the concept of framing and how window functions rely on sorting to provide the results.
My method will work on seconds minutes hours and can be adapted to weeks months.
