[postgis-users] building a polygon with variables

[Gold, Jack L (US SSA)]

I'm not even sure how to express this properly, but I'll try.  I'm trying to build a query which will select positions within a specified polygon.  I have the query:

SELECT * FROM positions WHERE ST_Within(geometry(positions.location), ST_GeomFromText('POLYGON((l b, r b, r t, l t, l b))'::text, 4326));

I want to be able to replace l, b, r, and t with variable values in a plpgsql function like so:

$BODY$
DECLARE
                l integer;
                r integer;
                b integer;
                t integer;
BEGIN

SELECT pli_config.filter_left_longitude INTO l FROM pli_config;
SELECT pli_config.filter_right_longitude INTO r FROM pli_config;
SELECT pli_config.filter_bottom_latitude INTO b FROM pli_config;
SELECT pli_config.filter_top_latitude INTO t FROM pli_config;

SELECT * FROM positions
  WHERE st_within(geometry(positions.location), st_geomfromtext('POLYGON((l b,r b,r t,l t,l b))'::text, 4326));

END;
$BODY$

The problem I have is I don't know the proper syntax to replace the variables in the single-quoted statement or even if it is possible.  Any ideas?

--Jack Gold
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