This article explains date time functions available in sql server with different examples.
Function
Determinism
DATEADD
Deterministic
DATEDIFF
DATENAME
Nondeterministic
DATEPART
Deterministic except when used as DATEPART (dw, date). dw, the weekday datepart, depends on the value set by SET DATEFIRST, which sets the first day of the week.
DAY
GETDATE
GETUTCDATE
MONTH
YEAR