PostGIS Custom Function to Create Polygon from Centroid

Needed to create a polygon from a point defining its size in both axes, here’s a little syntax sugar to make life easier.

CREATE OR REPLACE FUNCTION ST_PolygonFromCentroid(centroid geometry, xsize numeric, ysize numeric)
RETURNS geometry
AS $ST_PolygonFromCentroid$
SELECT ST_MakeEnvelope(
    ST_X(ST_Translate($1, -$2, -$3)),
    ST_Y(ST_Translate($1, -$2, -$3)),
    ST_X(ST_Translate($1, $2, $3)),
    ST_Y(ST_Translate($1, $2, $3))
);
$ST_PolygonFromCentroid$
LANGUAGE SQL;

Run it as:

SELECT ST_PolygonFromCentroid(ST_SetSRID(ST_MakePoint(13.912,50.633),4326), 1, 1);