Deterministic and Nondeterministic Functions

Deterministic functions always return the same result any time they are called with a specific set of input values and given the same state of the database. Nondeterministic functions may return different results each time they are called with a specific set of input values even if the database state that they access remains the same.

The following built-in functions from categories of built-in functions other than aggregate and string functions are always deterministic.

ABS	DATEDIFF	PARSENAME
ACOS	DAY	POWER
ASIN	DEGREES	RADIANS
ATAN	EXP	ROUND
ATN2	FLOOR	SIGN
CEILING	ISNULL	SIN
COALESCE	ISNUMERIC	SQUARE
COS	LOG	SQRT
COT	LOG10	TAN
DATALENGTH	MONTH	YEAR
DATEADD	NULLIF

The following functions are not always deterministic, but can be used in indexed views or indexes on computed columns when they are specified in a deterministic manner.

Function	Comments
CAST	Deterministic unless used with datetime, smalldatetime, or sql_variant.
CONVERT	Deterministic unless one of these conditions exists: Source type is sql_variant. Target type is sql_variant and its source type is nondeterministic. Source or target type is datetime or smalldatetime, the other source or target type is a character string, and a nondeterministic style is specified. To be deterministic, the style parameter must be a constant. Additionally, styles less than or equal to 100 are nondeterministic, except for styles 20 and 21. Styles greater than 100 are deterministic, except for styles 106, 107, 109 and 113.
CHECKSUM	Deterministic, with the exception of CHECKSUM(*).
ISDATE	Deterministic only if used with the CONVERT function, the CONVERT style parameter is specified and style is not equal to 0, 100, 9, or 109.
RAND	RAND is deterministic only when a seed parameter is specified.

All the configuration, cursor, metadata, security, and system statistical functions are nondeterministic. For a list of these functions, see Configuration Functions (Transact-SQL), Cursor Functions (Transact-SQL), Metadata Functions (Transact-SQL), Security Functions (Transact-SQL), and System Statistical Functions (Transact-SQL).
The following built-in functions from other categories are always nondeterministic.

@@CONNECTIONS	@@TOTAL_READ
@@CPU_BUSY	@@TOTAL_WRITE
@@DBTS	CURRENT_TIMESTAMP
@@IDLE	GETDATE
@@IO_BUSY	GETUTCDATE
@@MAX_CONNECTIONS	GET_TRANSMISSION_STATUS
@@PACK_RECEIVED	MIN_ACTIVE_ROWVERSION
@@PACK_SENT	NEWID
@@PACKET_ERRORS	NEWSEQUENTIALID
@@TIMETICKS	RAND
@@TOTAL_ERRORS	TEXTPTR