Catégories :: Fonctions géospatiales

ST_ASWKT , ST_ASTEXT¶

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

Voir aussi :: ST_ASEWKT

Syntaxe¶

Utilisez l’une des méthodes suivantes :

ST_ASWKT( <geography_or_geometry_expression> )

ST_ASTEXT( <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¶

ST_ASTEXT est un alias pour ST_ASWKT.
Pour renvoyer la sortie au format EWKT, utilisez plutôt ST_ASEWKT.

Exemples¶

GEOGRAPHY Examples¶

L’exemple suivant illustre la fonction ST_ASWKT :

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_astext(g)
    from geospatial_table
    order by id;
+-------------------------------------+
| ST_ASTEXT(G)                        |
|-------------------------------------|
| POINT(-122.35 37.55)                |
| LINESTRING(-124.2 42,-120.01 41.99) |
+-------------------------------------+

select st_aswkt(g)
    from geospatial_table
    order by id;
+-------------------------------------+
| ST_ASWKT(G)                         |
|-------------------------------------|
| POINT(-122.35 37.55)                |
| 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.

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

ALTER SESSION SET GEOMETRY_OUTPUT_FORMAT='WKT';
SELECT ST_ASWKT(g) FROM geometry_table;

+------------------------------+
| ST_ASWKT(G)                  |
|------------------------------|
| POINT(-122.35 37.55)         |
| LINESTRING(0.75 0.75,-10 20) |
+------------------------------+