Returns true if geometry A is fully contained within geometry B.
Syntax
boolean ST_Within(geometry A, geometry B)Parameters
| Parameter | Description |
|---|---|
A | The geometry to test for containment. |
B | The geometry that acts as the container. |
Usage notes
Same spatial reference identifier (SRID) required. Both geometries must use the same projection method and the same SRID.
Spatial equality. If both ST_Within(A, B) and ST_Within(B, A) return true, A and B are spatially equal.
Input validity. Pass only valid geometry objects. Invalid geometries return incorrect results.
GeometryCollection not supported. This function does not support GeometryCollection objects.
Index usage. ST_Within generates a bounding box and uses any available spatial indexes. To skip index usage, call _ST_Within instead.
Examples
Basic containment check
The following example checks whether a small polygon lies within a larger one.
SELECT ST_Within(
'POLYGON((1 1,1 2,2 2,2 1,1 1))'::geometry,
'POLYGON((0 0,0 3,3 3,3 0,0 0))'::geometry
);Output:
st_within
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