Issue with PostGIS ST_WITHIN

Question

Environment: PostgreSQL 11.4 with PostGIS 2.5.2

CREATE TABLE m_polygon (id SERIAL PRIMARY KEY, bounds POLYGON);

INSERT INTO m_polygon(bounds) VALUES(

'(0.0, 0.0), (0.0, 10.0), (10.0, 0.0), (10.0, 10.0), (0,0)'

);

SELECT ST_WITHIN(m_polygon.bounds , m_polygon.bounds ) FROM m_polygon;

I am getting the error message for SELECT statement above:

ERROR: function st_within(polygon, polygon) does not exist

HINT: No function matches the given name and argument types. You might

need to add explicit type casts

I was thinking what the reason for the error is: the ST_WITHIN arguments types should be GEOMETRY, but I am passing the POLYGONs.

However the following works:

SELECT ST_WITHIN(ST_MakePoint(1,1), ST_MakePoint(1,1) ) ;

Answer 1

SELECT ST_WITHIN(m_polygon.bounds , m_polygon.bounds ) FROM m_polygon;

Have you tried it without m_polygon for the Select? SELECT ST_WITHIN (bounds, bounds) FROM m_polygon;