Catégories :: Fonctions géospatiales

ST_ASEWKT¶

Given a value of type GEOGRAPHY or GEOMETRY, return the text (VARCHAR) representation of that value in EWKT (extended well-known text) format.

Voir aussi :: ST_ASWKT

Syntaxe¶

ST_ASEWKT( <geography_or_geometry_expression> )

Arguments¶

geography_or_geometry_expression: The argument must be an expression of type GEOGRAPHY or GEOMETRY.

Renvoie¶

Un VARCHAR.

Notes sur l’utilisation¶

For GEOGRAPHY objects, the SRID in the return value is always 4326. See the note on EWKT handling.
Pour renvoyer la sortie au format WKT, utilisez plutôt ST_ASWKT.

Exemples¶

GEOGRAPHY Examples¶

L’exemple suivant illustre la fonction ST_ASEWKT :

create table geospatial_table (id INTEGER, g GEOGRAPHY);
insert into geospatial_table values
    (1, 'POINT(-122.35 37.55)'), (2, 'LINESTRING(-124.20 42.00, -120.01 41.99)');

select st_asewkt(g)
    from geospatial_table
    order by id;
+-----------------------------------------------+
| ST_ASEWKT(G)                                  |
|-----------------------------------------------|
| SRID=4326;POINT(-122.35 37.55)                |
| SRID=4326;LINESTRING(-124.2 42,-120.01 41.99) |
+-----------------------------------------------+

GEOMETRY Examples¶

The example below demonstrates how to use the ST_ASEWKT function. The example returns the EWKT representations of two geometries that have different SRIDs.

CREATE OR REPLACE TABLE geometry_table (g GEOMETRY);
INSERT INTO geometry_table VALUES
  ('SRID=4326;POINT(-122.35 37.55)'),
  ('SRID=0;LINESTRING(0.75 0.75, -10 20)');

ALTER SESSION SET GEOMETRY_OUTPUT_FORMAT='EWKT';
SELECT ST_ASEWKT(g) FROM geometry_table;

+-------------------------------------+
| ST_ASEWKT(G)                        |
|-------------------------------------|
| SRID=4326;POINT(-122.35 37.55)      |
| SRID=0;LINESTRING(0.75 0.75,-10 20) |
+-------------------------------------+