postgres SQL, function - postgresql

Question

I want to create a function which returns how many levels the boss is above the person(calling the function).
Here is the way i would like to do it, but i don't quite know how SQL syntax works
http://pastebin.com/dyDaGwf9
the table looks like this:
workerid name chefid
1 Bob
2 Alice 1
3 Joe 1
4 John 2
5 Dirk 4
6 Ralf 2
7 Lisa 1
8 Lyn 3
the final result upon calling the function should look like this
function call:
Select workerid, name, rankFunction(workerid) from workers;
workerid name rank
1 Bob 0
2 Alice 1
3 Joe 1
4 John 2
5 Dirk 3
6 Ralf 2
7 Lisa 1
8 Lyn 2
Would be great if somebody could shed some light,
Thanks!

Answer 1

You don't need a function for this, just a recursive query (available as of version 8.4):
WITH RECURSIVE chef as (
SELECT workerid, name, chefid, 0 AS rank FROM workers WHERE chefid is null
UNION ALL
SELECT workers.workerid, workers.name, workers.chefid, rank + 1
FROM workers JOIN chef ON workers .chefid = chef.workerid
)
SELECT workerid, name, rank FROM chef ORDER BY workerid;

Answer 2

Here you are, a simple recursion:
CREATE OR REPLACE FUNCTION rankFunction(worker_id int)
RETURNS int AS
$BODY$
DECLARE
temp_chefid int;
BEGIN
temp_chefid := (SELECT chefid from workers where workerid = worker_id);
IF(temp_chefid IS NULL) THEN
RETURN 0;
ELSE RETURN 1 + rankFunction(temp_chefid);
END IF;
END;
$BODY$
LANGUAGE plpgsql VOLATILE