ST_Multi — Return the geometry as a MULTI* geometry.
geometry ST_Multi(
geometry geom)
;
Returns the geometry as a MULTI* geometry collection. If the geometry is already a collection, it is returned unchanged.
SELECT ST_AsText(ST_Multi('POLYGON ((10 30, 30 30, 30 10, 10 10, 10 30))')); st_astext ------------------------------------------------- MULTIPOLYGON(((10 30,30 30,30 10,10 10,10 30)))