Calculate time difference in T-SQL / SQL Server

This code snippet shows how to calculate time differences.

In SQL Server, DATEDIFF function can be used to find the differences between two dates/timestamps.

The syntax is:

DATEDIFF ( datepart , startdate , enddate )  

For parameter datepart, refer to the following table:

Code snippet

SELECT DATEDIFF(m,CAST('20171015' AS DATE), CAST('20191015' AS DATE)) AS Diff_Months;
SELECT DATEDIFF(d,CAST('20171015' AS DATE), CAST('20191015' AS DATE)) AS Diff_Days;
SELECT DATEDIFF(ww,CAST('20171015' AS DATE), CAST('20191015' AS DATE)) AS Diff_Weeks;
SELECT DATEDIFF(HH,CAST('20171015' AS DATE), CAST('20191015' AS DATE)) AS Diff_Hours;