Skip to main content

ST_Within

Tests whether geometry A is completely within geometry B.

Syntax​

ST_Within(geometry_a, geometry_b)

Parameters​

ParameterTypeDescription
geometry_aGeometryInner geometry
geometry_bGeometryOuter geometry

Returns​

TypeDescription
BooleanTrue if A is within B, false otherwise

Examples​

Test Point Within Polygon​

SELECT ST_Within(
    ST_Point(2, 2),
    ST_GeomFromText('POLYGON((0 0, 4 0, 4 4, 0 4, 0 0))')
);
-- Returns: true

Find Points Within Region​

SELECT * FROM points
WHERE ST_Within(geom, (
    SELECT geom FROM regions WHERE name = 'Zone A'
));

Classify Points by Region​

SELECT p.id, r.name as region
FROM points p
LEFT JOIN regions r ON ST_Within(p.geom, r.geom);

Notes​

  • A is within B means A is completely inside B
  • ST_Within(A, B) is equivalent to ST_Contains(B, A)
  • Point on polygon boundary returns false (use ST_CoveredBy for inclusive)
  • A geometry is within itself only if they're identical

See Also​