PLPGSQL how to use function parameters? - postgresql

Question

WORKING CODE AT THE END
I'm trying to get along with plpgsql but it's giving me a hard time. I'm trying to make a function on the database that will be called by my server to expand or create my terrain. I can't make it compile, no matter what I try, it blocks on the first usage of one of the two parameters the function has.
I havec tried sevral manners of declaring the parameters (refering to them as ALIAS FOR $1 or declaring them with a name as the following code shows) I also tried to change the parameter type to INTEGER or NUMERIC.
CREATE FUNCTION public.generate_terrain (
inner NUMERIC,
outer NUMERIC
)
RETURNS void AS
$body$
DECLARE
q NUMERIC;
r NUMERIC;
BEGIN
q := -outer;
r := -outer;
WHILE q < outer DO
WHILE r < outer DO
IF(r > -inner AND r < inner AND q > -inner AND q > inner) THEN
r := inner;
END IF;;
--insert into public.t_cell (coo_q, coo_r) values (q,r);
RAISE NOTICE 'Cell %,%', q,r;
r := r + 1;
END WHILE;
q := q + 1;
END WHILE;
END;
$body$
LANGUAGE 'plpgsql'
VOLATILE
CALLED ON NULL INPUT
SECURITY INVOKER
PARALLEL UNSAFE;
I get this error message when I try to compile it :
ERROR: syntax error at end of input
LINE 8: q := -outer;
^
I cannot have my client do the loop and then push the results onto the database it would generate to much traffic I want to have my database do this on it's own thus the need to be able to compile this. Please Help !
EDIT 1
I forgot to explain what i wanted this function to do : I need a function that populates my database with coherent "cells" of a carthesian grid map (q = x axis, r = y axis because in reality it's hexagonal map). This function must be able to be called to expand them map so if my initial call is generate_terrain(0,2) it must produce the followin terrain :
#####
#####
##0##
#####
#####
(0 is the center of the grid (0,0))
where the coordinates range from (-2,-2) as bottom left up to (2,2) on the top right corner. Later, when i need to expand the map I must be able to call generate_terrain(3,4) to generate the following cells of my terrain :
#########
#########
## ##
## ##
## 0 ##
## ##
## ##
#########
#########
(0 is the center of the grid (0,0))
Where the coordinates range from (-4,-4) as bottom left up to (4,4) on the top right corner but the inner "square" is already present in the database
The function I ended up using and that seems to work is the following :
CREATE OR REPLACE FUNCTION public.generate_terrain (
_inner integer,
_outer integer
)
RETURNS integer AS
$body$
DECLARE
q integer = 0;
r integer = 0;
BEGIN
q := q - _outer;
r := r - _outer;
WHILE q <= _outer
LOOP
WHILE r <= _outer
LOOP
-- This condition is to skip the inner square that is already
-- present in the database.
IF r > -_inner
AND r < _inner
AND q > -_inner
AND q < _inner THEN
r := _inner;
END IF;
--insert into public.t_cell (coo_q, coo_r) values (q, r);
RAISE NOTICE 'Cell %,%', q,r;
r := r + 1;
END LOOP;
q := q + 1;
r := - _outer;
END LOOP;
RETURN 1;
END;
$body$
LANGUAGE 'plpgsql'

Answer 1

Besides using reserved words like a_horse pointed out, you have several syntax violations. This would work:
CREATE OR REPLACE FUNCTION public.generate_terrain (_inner NUMERIC, _outer NUMERIC)
RETURNS void AS
$func$
DECLARE
q NUMERIC := -_outer;
r NUMERIC := -_outer;
BEGIN
WHILE q < _outer
LOOP -- !
WHILE r < _outer
LOOP -- !
IF r > -_inner
AND r < _inner
AND q > -_inner
AND q > _inner THEN -- ??
r := _inner;
END IF; -- !
--insert into public.t_cell (coo_q, coo_r) values (q,r);
RAISE NOTICE 'Cell %,%', q,r;
r := r + 1;
END LOOP; -- !
q := q + 1;
END LOOP; -- !
END
$func$ LANGUAGE plpgsql;
But this seems needlessly twisted. _inner is never used at all. Did you by any chance mean to write q < _inner? (Still odd.)
Else you can just use this instead:
CREATE OR REPLACE FUNCTION public.generate_terrain_simple (_outer int)
RETURNS void AS
$func$
INSERT INTO public.t_cell (coo_q, coo_r)
SELECT -_outer, g FROM generate_series (-_outer, _outer -1) g
$func LANGUAGE sql;

Answer 2

Minor optimization for Erwin Last Query.
create or replace function
public.generate_terrain_simple_1(_outer int)
returns void as $$
declare _x int; _y int;
begin
<<test>>
for _x, _y in
select -_outer, g from generate_series(-_outer,_outer - 1) g
loop
raise info 'test % %', _x,_y;
end loop test;
end
$$ language plpgsql;
select * from generate_terrain_simple_1(4);
_x will be the same as -4, _y will from -4 to 3