Catégories :: Fonctions géospatiales

ST_ASEWKB¶

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

Voir aussi :: ST_ASWKB

Syntaxe¶

ST_ASEWKB( <geography_or_geometry_expression> )

Arguments¶

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

Renvoie¶

Une valeur de type BINARY.

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 WKB, utilisez plutôt ST_ASWKB.

Exemples¶

GEOGRAPHY Examples¶

L’exemple suivant illustre la fonction ST_ASEWKB. Pour la sortie EWKB, il est supposé que le paramètre BINARY_OUTPUT_FORMAT est défini sur HEX (la valeur par défaut du paramètre).

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_asewkb(g)
    from geospatial_table
    order by id;
+--------------------------------------------------------------------------------------------+
| ST_ASEWKB(G)                                                                               |
|--------------------------------------------------------------------------------------------|
| 0101000020E61000006666666666965EC06666666666C64240                                         |
| 0102000020E610000002000000CDCCCCCCCC0C5FC00000000000004540713D0AD7A3005EC01F85EB51B8FE4440 |
+--------------------------------------------------------------------------------------------+

GEOMETRY Examples¶

The example below demonstrates how to use the ST_ASEWKB function. The example returns the EWKB 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)');

SELECT ST_ASEWKB(g) FROM geometry_table;

+--------------------------------------------------------------------------------------------+
| ST_ASEWKB(G)                                                                               |
|--------------------------------------------------------------------------------------------|
| 0101000020E61000006666666666965EC06666666666C64240                                         |
| 01020000200000000002000000000000000000E83F000000000000E83F00000000000024C00000000000003440 |
+--------------------------------------------------------------------------------------------+