Geometry values stored in a table can be fetched in internal format. You can also convert them into WKT or WKB format.
Fetching spatial data in internal format:
Fetching geometry values using internal format can be useful in table-to-table transfers:
CREATE TABLE geom2 (g GEOMETRY) SELECT g FROM geom;
Fetching spatial data in WKT format:
The AsText() function converts a geometry
from internal format into a WKT string.
SELECT AsText(g) FROM geom;
Fetching spatial data in WKB format:
The AsBinary() function converts a
geometry from internal format into a BLOB
containing the WKB value.
SELECT AsBinary(g) FROM geom;