Should I add set nocount for functions?

Question

I've been reading about the benefits for all triggers and procedures having "set nocount on" implemented unless you make use of DONE_IN_PROC.

I have a scalar-valued function that is called from an update trigger to calculate the sum of values across multiple tables.

Searching msdn and past articles, I haven't been able to find an explicit example of a function using set nocounton.

What is the impact on a function to include or exclude 'set nocount on'? Is there a point or code smell in functions that should indicate the addition of set nocount on?

Answer 1

Functions cannot return data to a client so I can't think of any use of SET NOCOUNT ON. If you do try to add it a function you'll get an error. SQL Server considers it to cause a side effect:

function_body

Specifies that a series of Transact-SQL statements, which together do not produce a side effect such as modifying a table, define the value of the function.

For example, the follow code throws an error:

CREATE FUNCTION X_JRO_TEST() 
RETURNS INT
AS
BEGIN
SET NOCOUNT ON;
RETURN 1;
END;

Msg 443, Level 16, State 15, Procedure X_JRO_TEST, Line 5

Invalid use of a side-effecting operator 'SET OPTION ON' within a function.