Elapsed Time Calculation on SQL Server with dateDiff

[Costas]

//https://stackoverflow.com/questions/4073340/using-datediff-to-find-duration-in-minutes

DECLARE @t1 DATETIME='2020-11-11 11:28:35'
DECLARE @t2 DATETIME=  GETDATE()
print  CAST(dateDiff(second,@t1,@t2) as INT)

/*
possible values
second
minute
millisecond
*/