-- The following table is created:

CREATE TABLE srid_test(g1 ST_Geometry);

-- In the next statement a ST_Point geometry located at 
-- coordinate (10.01,50.76) is inserted into the geometry column g1.
-- When the ST_Point geometry was created by the ST_PointFromText
-- function it was assigned the SRID value of 1000.

INSERT INTO srid_test VALUES(
   ST_PointFromText('point(10.01 50.76)',1000)
);

-- The ST_SRID function returns the spatial reference ID of the geometry
-- just entered.

SELECT ST_SRID(g1)
   FROM srid_test;