postgresql function creation gives syntax error - database

Question

I am writing a postgresql function but I cannot seem to find where the error is. Postgresql is at version 9.4.
The following is the function:
CREATE FUNCTION custom_function1()
RETURNS trigger
LANGUAGE plpgsql
AS
$$
DECLARE base_val integer;
BEGIN
base_val := (EXTRACT(YEAR FROM now())::integer * 10000000000);
IF (currval('custom_sequence') < base_val) THEN
setval('custom_sequence', base_val);
END IF;
NEW.id := custom_function2();
RETURN NEW;
END;
$$;
My custom_sequence is in the format YYYY0000000000 (ex. 20150000000000).
So what this basically does (should do) is it checks if the base_val (minimum value for current year) is greater then the currval (current custom_sequence value) and updates the custom_sequence value. Then it returns a new value for that sequence generated with the function custom_function2 (which formats it slighly).
When I try to execute this it gives me:
syntax error at or near "setval"
I am pretty new to both postgresql and writing functions so I am probably not seeying an obvious error. If someone could help me it would be highly appreciated, thank you.

Answer 1

The error is related to what's explained in the doc here:
40.5.2 Executing a Command With No Result
[...]
Sometimes it is useful to evaluate an expression or SELECT query but
discard the result, for example when calling a function that has
side-effects but no useful result value. To do this in PL/pgSQL, use
the PERFORM statement:
PERFORM query;
You should write:
PERFORM setval('custom_sequence', base_val);