How do I integrate a FOR loop into my dynamic queries? - postgresql

Question

I am trying to run a dynamic query. I have a static query that works :
CREATE OR REPLACE
FUNCTION update_points_in_polygon(
)
RETURNS trigger LANGUAGE plpgsql AS $function$
-- Rule for clarity : one filter per function. Can choose three options : point count unit count and label concat
-- the one rule will be applied to all 3 options if they are selected
DECLARE tmprow record;
BEGIN
FOR tmprow IN
SELECT c.objectid, count(a.*) point_count
FROM sandbox.simple_address a
JOIN sandbox.polygon_address_units c
ON st_intersects(a.wkb_geometry, c.wkb_geometry)
WHERE st_intersects(c.wkb_geometry, NEW.wkb_geometry)
GROUP BY c.objectid -- tmp TABLE fetchin nb OF addresses IN a polygon WHERE polygon interects point
LOOP
UPDATE sandbox.polygon_address_units
SET address_count = tmprow.point_count
WHERE objectid = tmprow.objectid; -- UPDATE point_count COLUMN OF TABLES fetched IN FIRST SELECT
END LOOP;
RETURN NEW;
END;
$function$;
When I try to replace the loop like this :
EXECUTE 'FOR tmprow IN
SELECT c.objectid, count(a.*) point_count
FROM sandbox.simple_address a
JOIN sandbox.polygon_address_units c
ON st_intersects(a.wkb_geometry, c.wkb_geometry)
WHERE st_intersects(c.wkb_geometry, NEW.wkb_geometry)
GROUP BY c.objectid
LOOP
UPDATE sandbox.polygon_address_units
SET address_count = tmprow.point_count
WHERE objectid = tmprow.objectid;
END LOOP;';
I get the following message :
SQL Error [42601]: ERROR: syntax error at or near "FOR" Where:
PL/pgSQL function update_points_in_polygon() line 7 at EXECUTE
The aim is to be able to define table_names and columns dynamically. I've also tried to make two execute statements and keep the LOOP in plpgsql instead of plain SQL that's run with EXECUTE:
CREATE OR REPLACE
FUNCTION update_points_in_polygon(
)
RETURNS trigger LANGUAGE plpgsql AS $function$
-- Rule for clarity : one filter per function. Can choose three options : point count unit count and label concat
-- the one rule will be applied to all 3 options if they are selected
DECLARE tables_schema varchar;
DECLARE polygon_table_name varchar;
DECLARE polygon_point_count_column_name varchar;
DECLARE point_table_name varchar;
DECLARE tmprow record;
BEGIN
tables_schema = TG_ARGV[0]; -- frontier_ftth
polygon_table_name = TG_ARGV[1]; -- fdh
polygon_point_count_column_name = TG_ARGV[2]; -- point_count
point_table_name = TG_ARGV[4];
FOR tmprow IN
EXECUTE format('SELECT c.objectid, count(a.*) point_count
FROM %I.%I a
JOIN %I.%I c
ON st_intersects(a.wkb_geometry, c.wkb_geometry)
WHERE st_intersects(c.wkb_geometry, st_geomFromText(''%s'', 4326))
GROUP BY c.objectid',
tables_schema, point_table_name, tables_schema, polygon_table_name,
st_astext(st_geomfromewkb(NEW.wkb_geometry)))
LOOP
EXECUTE format('UPDATE %I.%I c1
SET %I = tmprow.point_count
WHERE c1.objectid = tmprow.objectid',
tables_schema, polygon_table_name, polygon_point_count_column_name);
END LOOP;
RETURN NEW;
END;
$function$
With this version of the function, I get the following error :
SQL Error [22004]: ERROR: null values cannot be formatted as an SQL identifier
Where: PL/pgSQL function update_points_in_polygon() line 17 at FOR over EXECUTE statement
This is a barebones version of my setup :
CREATE TABLE sandbox.simple_address (
objectid serial4 NOT NULL,
wkb_geometry geometry(point, 4326) NULL,
);
CREATE TABLE sandbox.polygon_address_units (
objectid serial4 NOT NULL,
address_count int4 NULL,
wkb_geometry geometry(multipolygon, 4326) NULL,
);
CREATE TRIGGER onallactions AFTER INSERT
OR UPDATE ON
sandbox.simple_address FOR EACH ROW
WHEN ((pg_trigger_depth() < 1)) EXECUTE PROCEDURE
update_points_in_polygon(
'sandbox', 'polygon_address_units', 'address_count',
'simple_address');
INSERT INTO sandbox.polygon_address_units(wkb_geometry)
VALUES(ST_SetSRID(st_astext(st_geomfromtext('MULTIPOLYGON (((-1 1, 1 1, 1 -1, -1 -1, -1 1)))')),4326));
INSERT INTO sandbox.simple_address(wkb_geometry)
VALUES(ST_SetSRID(st_astext(st_geomfromtext('POINT(0 0)')),4326));
How do use these two queries to properly update the number_of_points column in my polygon layers when I add a point that intersects it ? There might be multiple polygons to update.
EDIT: The solution was to call tmprow to format the second string
FOR tmprow IN
EXECUTE format('SELECT c.objectid, count(a.*) point_count
FROM %I.%I a
JOIN %I.%I c
ON st_intersects(a.wkb_geometry, c.wkb_geometry)
WHERE st_intersects(c.wkb_geometry, st_geomFromText(''%s'', 4326))
GROUP BY c.objectid',
tables_schema, point_table_name, tables_schema, polygon_table_name,
st_astext(st_geomfromewkb(NEW.wkb_geometry)))
LOOP
EXECUTE format('UPDATE %I.%I c1
SET %I = %s
WHERE c1.objectid = %s ',
tables_schema, polygon_table_name, polygon_point_count_column_name, tmprow.point_count, tmprow.objectid);
END LOOP;
RETURN NEW;
END;
$function$