CREATE TABLE krawedzie(nazwa text,geometria geometry);

select * from krawedzie;

INSERT INTO krawedzie VALUES('krawedz1',
ST_GeomFromEWKT('LINESTRING (1 1, 8 1)'));
INSERT INTO krawedzie VALUES('krawedz2',
ST_GeomFromEWKT('LINESTRING (8 1, 8 6)'));
INSERT INTO krawedzie VALUES('krawedz3',
ST_GeomFromEWKT('LINESTRING (8 6, 1 6)'));
INSERT INTO krawedzie VALUES('krawedz4',
ST_GeomFromEWKT('LINESTRING (1 6, 1 1)'));


CREATE OR REPLACE FUNCTION azymut2(pkt1 geometry,pkt geometry) RETURNS FLOAT LANGUAGE plpgsql AS $$
	DECLARE
	dx FLOAT;
	dy FLOAT;
	azym FLOAT;
   BEGIN

	 dx := ST_X(pkt) - ST_X(pkt1);
	 dy := ST_Y(pkt) - ST_Y(pkt1);

	azym := atan2(dx,dy);
	RETURN azym;
   END
   $$ ;

   ALTER TABLE krawedzie ADD COLUMN azimuth FLOAT;




select * from krawedzie;