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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.

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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 |
+--------------------------------------------------------------------------------------------+
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