Table of Contents
This section describes the standard spatial data formats that are used to represent geometry objects in queries. They are:
Well-Known Text (WKT) format
Well-Known Binary (WKB) format
Internally, MySQL stores geometry values in a format that is not identical to either WKT or WKB format.
The Well-Known Text (WKT) representation of Geometry is designed to exchange geometry data in ASCII form.
Examples of WKT representations of geometry objects are:
A Point:
POINT(15 20)
Note that point coordinates are specified with no separating comma.
A LineString with four points:
LINESTRING(0 0, 10 10, 20 25, 50 60)
A Polygon with one exterior ring and one interior ring:
POLYGON((0 0,10 0,10 10,0 10,0 0),(5 5,7 5,7 7,5 7, 5 5))
A MultiPoint with three Point values:
MULTIPOINT(0 0, 20 20, 60 60)
A MultiLineString with two LineString values:
MULTILINESTRING((10 10, 20 20), (15 15, 30 15))
A MultiPolygon with two Polygon values:
MULTIPOLYGON(((0 0,10 0,10 10,0 10,0 0)),((5 5,7 5,7 7,5 7, 5 5)))
A GeometryCollection consisting of two Point values and one LineString:
GEOMETRYCOLLECTION(POINT(10 10), POINT(30 30), LINESTRING(15 15, 20 20))
A Backus-Naur grammar that specifies the formal production rules for writing WKT values may be found in the OGC specification document referenced near the beginning of this chapter.