11.17.3.1. Well-Known Text (WKT) Format

The Well-Known Text (WKT) representation of Geometry is designed to exchange geometry data in ASCII form. For a Backus-Naur grammar that specifies the formal production rules for writing WKT values, see the OpenGIS specification document referenced in Section 11.17, “Spatial Extensions”.

Examples of WKT representations of geometry objects:

  • A Point:

    POINT(15 20)
    

    Note that point coordinates are specified with no separating comma. This differs from the syntax for the SQL POINT() function, which requires a comma between the coordinates. Take care to use the syntax appropriate to the context of a given spatial operation. For example, the following statements both extract the X-coordinate from a Point object. The first produces the object directly using the POINT() function. The second uses a WKT representation converted to a Point with GeomFromText().

    mysql> SELECT X(POINT(15, 20));
    +------------------+
    | X(POINT(15, 20)) |
    +------------------+
    |               15 |
    +------------------+
    
    mysql> SELECT X(GeomFromText('POINT(15 20)'));
    +---------------------------------+
    | X(GeomFromText('POINT(15 20)')) |
    +---------------------------------+
    |                              15 |
    +---------------------------------+
    
  • A LineString with four points:

    LINESTRING(0 0, 10 10, 20 25, 50 60)
    

    Note that point coordinate pairs are separated by commas.

  • 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))
    
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