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MySQL 8.0 Reference Manual  /  ...  /  Geometry Format Conversion Functions

Pre-General Availability Draft: 2017-11-22

12.15.6 Geometry Format Conversion Functions

MySQL supports the functions listed in this section for converting geometry values from internal geometry format to WKT or WKB format, or for swapping the order of X and Y coordinates.

There are also functions to convert a string from WKT or WKB format to internal geometry format. See Section 12.15.3, “Functions That Create Geometry Values from WKT Values”, and Section 12.15.4, “Functions That Create Geometry Values from WKB Values”.

Functions such as ST_GeomFromText() that accept WKT geometry collection arguments understand both OpenGIS 'GEOMETRYCOLLECTION EMPTY' standard syntax and MySQL 'GEOMETRYCOLLECTION()' nonstandard syntax. Functions such as ST_AsWKT() that produce WKT values produce 'GEOMETRYCOLLECTION EMPTY' standard syntax:

mysql> SET @s1 = ST_GeomFromText('GEOMETRYCOLLECTION()');
mysql> SET @s2 = ST_GeomFromText('GEOMETRYCOLLECTION EMPTY');
mysql> SELECT ST_AsWKT(@s1), ST_AsWKT(@s2);
+--------------------------+--------------------------+
| ST_AsWKT(@s1)            | ST_AsWKT(@s2)            |
+--------------------------+--------------------------+
| GEOMETRYCOLLECTION EMPTY | GEOMETRYCOLLECTION EMPTY |
+--------------------------+--------------------------+

Unless otherwise specified, functions in this section handle their arguments as follows:

  • If any argument is NULL, the return value is NULL.

  • If a geometry argument is not a syntactically well-formed geometry, an ER_GIS_INVALID_DATA error occurs.

  • If an options argument is invalid, an error occurs to indicate why.

  • Otherwise, the return value is non-NULL.

These functions are available for format conversions or coordinate swapping:

  • ST_AsBinary(g [, options]), ST_AsWKB(g [, options])

    Converts a value in internal geometry format to its WKB representation and returns the binary result.

    The function return value has geographic coordinates (latitude, longitude) in the order specified by the spatial reference system that applies to the geometry argument. An optional options argument may be given to override the default axis order.

    ST_AsBinary() and ST_AsWKB() handle their arguments as described in the introduction of this section.

    mysql> SET @g = ST_LineFromText('LINESTRING(0 5,5 10,10 15)', 4326);
    mysql> SELECT ST_AsText(ST_GeomFromWKB(ST_AsWKB(@g)));
    +-----------------------------------------+
    | ST_AsText(ST_GeomFromWKB(ST_AsWKB(@g))) |
    +-----------------------------------------+
    | LINESTRING(5 0,10 5,15 10)              |
    +-----------------------------------------+
    mysql> SELECT ST_AsText(ST_GeomFromWKB(ST_AsWKB(@g, 'axis-order=long-lat')));
    +----------------------------------------------------------------+
    | ST_AsText(ST_GeomFromWKB(ST_AsWKB(@g, 'axis-order=long-lat'))) |
    +----------------------------------------------------------------+
    | LINESTRING(0 5,5 10,10 15)                                     |
    +----------------------------------------------------------------+
    mysql> SELECT ST_AsText(ST_GeomFromWKB(ST_AsWKB(@g, 'axis-order=lat-long')));
    +----------------------------------------------------------------+
    | ST_AsText(ST_GeomFromWKB(ST_AsWKB(@g, 'axis-order=lat-long'))) |
    +----------------------------------------------------------------+
    | LINESTRING(5 0,10 5,15 10)                                     |
    +----------------------------------------------------------------+
  • ST_AsText(g [, options]), ST_AsWKT(g [, options])

    Converts a value in internal geometry format to its WKT representation and returns the string result.

    The function return value has geographic coordinates (latitude, longitude) in the order specified by the spatial reference system that applies to the geometry argument. An optional options argument may be given to override the default axis order.

    ST_AsText() and ST_AsWKT() handle their arguments as described in the introduction of this section.

    mysql> SET @g = 'LineString(1 1,2 2,3 3)';
    mysql> SELECT ST_AsText(ST_GeomFromText(@g));
    +--------------------------------+
    | ST_AsText(ST_GeomFromText(@g)) |
    +--------------------------------+
    | LINESTRING(1 1,2 2,3 3)        |
    +--------------------------------+

    Output for MultiPoint values includes parentheses around each point. For example:

    mysql> SELECT ST_AsText(ST_GeomFromText(@mp));
    +---------------------------------+
    | ST_AsText(ST_GeomFromText(@mp)) |
    +---------------------------------+
    | MULTIPOINT((1 1),(2 2),(3 3))   |
    +---------------------------------+
  • ST_SwapXY(g)

    Accepts an argument in internal geometry format, swaps the X and Y values of each coordinate pair within the geometry, and returns the result.

    ST_SwapXY() handles its arguments as described in the introduction of this section.

    mysql> SET @g = ST_LineFromText('LINESTRING(0 5,5 10,10 15)');
    mysql> SELECT ST_AsText(@g);
    +----------------------------+
    | ST_AsText(@g)              |
    +----------------------------+
    | LINESTRING(0 5,5 10,10 15) |
    +----------------------------+
    mysql> SELECT ST_AsText(ST_SwapXY(@g));
    +----------------------------+
    | ST_AsText(ST_SwapXY(@g))   |
    +----------------------------+
    | LINESTRING(5 0,10 5,15 10) |
    +----------------------------+

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