ST_Within

Signature

BOOLEAN ST_Within(GEOMETRY geomA, GEOMETRY geomB);

Description

Returns TRUE if geomA is within geomB.

Within means that every point of geomA is a point of geomB, and the interiors of the two geometries have at least one point in common.

As a consequence, the following are equivalent:

ST_Within(geomA, geomB) and ST_Within(geomB, geomA) are true.
ST_Equals(geomA, geomB) is true.

Warning

This function does not work on GEOMETRYCOLLECTIONs

Note

Implements the OpenGIS Simple Features Implementation Specification for SQL version 1.2.1

Warning

This predicate does not yet support spatial indices, but it will in a future release. Use it in conjunction with && operator. See here for more details.

Examples

Cases where `ST_Within` is true

SELECT ST_Within(geomA, geomB) FROM input_table;
-- Answer:    TRUE

geomA POLYGON	geomB POLYGON
POLYGON((2 2, 7 2, 7 5, 2 5, 2 2))	POLYGON((1 1, 8 1, 8 7, 1 7, 1 1))

geomA LINESTRING	geomB POLYGON
LINESTRING(2 6, 6 2)	POLYGON((1 1, 8 1, 8 7, 1 7, 1 1))

geomA POINT	geomB POLYGON
POINT(4 4)	POLYGON((1 1, 8 1, 8 7, 1 7, 1 1))

geomA POLYGON	geomB POLYGON
POLYGON((1 2, 6 2, 6 5, 1 5, 1 2))	POLYGON((1 1, 8 1, 8 7, 1 7, 1 1))

geomA LINESTRING	geomB POLYGON
LINESTRING(1 2, 1 6, 5 2)	POLYGON((1 1, 8 1, 8 7, 1 7, 1 1))

geomA LINESTRING	geomB LINESTRING
LINESTRING(3 5, 5 3)	LINESTRING(2 1, 5 3, 2 6)

geomA POINT	geomB LINESTRING
POINT(4 4)	LINESTRING(2 1, 5 3, 2 6)

Cases where `ST_Within` is false

SELECT ST_Within(geomA, geomB) FROM input_table;
-- Answer:    FALSE

geomA POLYGON	geomB POLYGON
POLYGON((0 2, 5 2, 5 5, 0 5, 0 2))	POLYGON((1 1, 8 1, 8 7, 1 7, 1 1))

geomA LINESTRING	geomB POLYGON
LINESTRING(2 6, 0 8)	POLYGON((1 1, 8 1, 8 7, 1 7, 1 1))

geomA POINT	geomB POLYGON
POINT(8 4)	POLYGON((1 1, 8 1, 8 7, 1 7, 1 1))

geomA POINT	geomB POLYGON
POINT(8 4)	POLYGON((1 1, 7 1, 7 7, 1 7, 1 1))