ST_Different-ApsaraDB RDS(RDS)-阿里云帮助中心

Returns the part of geometry A that does not intersect with geometry B.

Syntax

geometry ST_Difference(geometry geomA, geometry geomB);

Parameters

Parameter	Description
`geomA`	The first geometry object.
`geomB`	The second geometry object.

Usage notes

If geomA is completely contained within geomB, the function returns an empty geometry.
The order of the input geometry objects affects the output. ST_Difference(A, B) and ST_Difference(B, A) produce different results.
GeometryCollection objects are not supported.
For 3D geometries, the function processes only the X and Y coordinates but preserves the original Z coordinates in the output.

Example

SELECT ST_AsText(ST_Difference('LINESTRING(0 0,0 2)'::geometry,'LINESTRING(0 1,0 3)'::geometry));
      st_astext
---------------------
 LINESTRING(0 0,0 1)
(1 row)