ST_BUFFER

Returns a geometry representing all points within a given distance of the geometry. This standard-compliant function creates a buffer zone around the object.

Syntax

ST_BUFFER(g1,r)
BUFFER(g1,r)

Description

Returns a geometry that represents all points whose distance from geometry g1 is less than or equal to distance, or radius, r.

Uses for this function could include creating for example a new geometry representing a buffer zone around an island.

BUFFER() is a synonym.

Examples

Determining whether a point is within a buffer zone:

SET @g1 = ST_GEOMFROMTEXT('POLYGON((10 10, 10 20, 20 20, 20 10, 10 10))');

SET @g2 = ST_GEOMFROMTEXT('POINT(8 8)');

SELECT ST_WITHIN(@g2,ST_BUFFER(@g1,5));
+---------------------------------+
| ST_WITHIN(@g2,ST_BUFFER(@g1,5)) |
+---------------------------------+
|                               1 |
+---------------------------------+

SELECT ST_WITHIN(@g2,ST_BUFFER(@g1,1));
+---------------------------------+
| ST_WITHIN(@g2,ST_BUFFER(@g1,1)) |
+---------------------------------+
|                               0 |
+---------------------------------+

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