ST_ASTEXT
Descriptionβ
Converts a geometric object into its WKT (Well-Known Text) text representation. WKT is a text-based format for representing geospatial data, widely used in Geographic Information Systems (GIS).
Currently supported geometric types include: Point, LineString, Polygon, MultiPolygon, Circle.
Aliasesβ
- ST_ASWKT
Sytaxβ
ST_ASTEXT( <geo>)
Parameters
Parameter | Description |
---|---|
<geo> | The geometric object to be converted to WKT format. |
Return valueβ
Returns the WKT text representation of the geometric object.
ST_ASTEXT has the following edge cases:
- If the input parameter is NULL, returns NULL.
Exampleβ
Point object conversion
SELECT ST_AsText(ST_Point(24.7, 56.7));
+---------------------------------+
| st_astext(st_point(24.7, 56.7)) |
+---------------------------------+
| POINT (24.7 56.7) |
+---------------------------------+
LineString object conversion
mysql> SELECT ST_AsText(ST_GeometryFromText("LINESTRING (1 1, 2 2)"));
+---------------------------------------------------------+
| ST_AsText(ST_GeometryFromText("LINESTRING (1 1, 2 2)")) |
+---------------------------------------------------------+
| LINESTRING (1 1, 2 2) |
+---------------------------------------------------------+
Polygon object conversion
mysql> SELECT ST_AsText(ST_Polygon("POLYGON ((114.104486 22.547119,114.093758 22.547753,114.096504 22.532057,114.104229 22.539826,114.106203 22.542680,114.104486 22.547119))"));
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| ST_AsText(ST_Polygon("POLYGON ((114.104486 22.547119,114.093758 22.547753,114.096504 22.532057,114.104229 22.539826,114.106203 22.542680,114.104486 22.547119))")) |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| POLYGON ((114.104486 22.547119, 114.093758 22.547753, 114.096504 22.532057, 114.104229 22.539826, 114.106203 22.54268, 114.104486 22.547119)) |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------+
MultiPolygon object conversion
mysql> SELECT ST_AsText(ST_GeometryFromText("MULTIPOLYGON (((0 0, 1 0, 1 1, 0 1, 0 0)), ((2 2, 3 2, 3 3, 2 3, 2 2)))"));
+-----------------------------------------------------------------------------------------------------------+
| ST_AsText(ST_GeometryFromText("MULTIPOLYGON (((0 0, 1 0, 1 1, 0 1, 0 0)), ((2 2, 3 2, 3 3, 2 3, 2 2)))")) |
+-----------------------------------------------------------------------------------------------------------+
| MULTIPOLYGON (((0 0, 1 0, 1 1, 0 1, 0 0)), ((2 2, 3 2, 3 3, 2 3, 2 2))) |
+-----------------------------------------------------------------------------------------------------------+
Circle object conversion
mysql> SELECT ST_AsText(ST_Circle(116.39748, 39.90882, 0.5));
+------------------------------------------------+
| ST_AsText(ST_Circle(116.39748, 39.90882, 0.5)) |
+------------------------------------------------+
| CIRCLE ((116.39748 39.90882), 0.5) |
+------------------------------------------------+
NULL input
mysql> SELECT ST_AsText(NULL);
+-----------------+
| ST_AsText(NULL) |
+-----------------+
| NULL |
+-----------------+