Returns a geometry that represents all points whose distance from the geometry value g  is less than or equal to a distance of d . The result is in the same SRS as the geometry argument. 

If the geometry argument is empty, ST_Buffer()  returns an empty geometry. 

If the distance is 0, ST_Buffer()  returns the geometry argument unchanged: 

mysql> SET @pt = ST_GeomFromText(’POINT(0 0)’); mysql> SELECT ST_AsText(ST_Buffer(@pt, 0)); +------------------------------+ | ST_AsText(ST_Buffer(@pt, 0)) | +------------------------------+ | POINT(0 0) | 

