Name
ST_Within — Tests if a Geometry is spatially within another Geometry.
Synopsis
boolean ST_Within(bytea GeomA, bytea GeomB);
Description
Tests if a Geometry is spatially within another Geometry. The within predicate has the following equivalent definitions:
Every point of Geometry A is a point of Geometry B, and the interiors of the two geometries have at least one point in common.
In mathematical terms: a.Within(b) «-» (a ∩ b = a) Ʌ (I(a) ∩I(b) ≠ ᴓ)
The DE-9IM Intersection Matrix for the two geometries is T*F**F*** *
ST_Within is the inverse of ST_Contains
![[Note]](images/note.png) | |
GeometryCollections are unsupported |
Coordinate Dimensions
| 2D | 3D | M |
|---|---|---|
 | | |
Spatial Standards Support
| OGC SFS for SQL. 1.1 (1999) | OGC SFS for SQL. 1.1.0 (2005) | OGC SFS for SQL. 1.2.0 (2006) | SQL-MM Part 3 |
|---|---|---|---|
| 2.1.1.2 , 2.1.13.3 | 7.2.19.1 | 7.2.8.1 | 5.1.30 |
Examples
SELECT ST_Within(PA,PB) as AwithinB, ST_Contains(PB,PA) as BcontainsA, ST_Within(PB,PA) as BwithinA
from (SELECT ST_GeomFromText('POLYGON ((3 5, 3 8, 6 8, 6 5, 3 5))') as PA,
ST_GeomFromText('POLYGON ((1 1, 1 9, 8 9, 8 1, 1 1))') as PB) as foo;
--Result
awithinb | bcontainsa | bwithina
----------+------------+----------
t | t | f |