ST_CIRCLE

Description

Converts a WKT (Well-Known Text) into a circle on the Earth's spherical surface.

Sytax

ST_CIRCLE( <center_lng>, <center_lat>, <radius>)

Parameters

Parameter	Description
<center_lng>	Longitude of the circle's center, of type DOUBLE, with a valid range of [-180, 180]
<center_lat>	Latitude of the circle's center, of type DOUBLE, with a valid range of [-180, 180]
<radius>	Radius of the circle, of type DOUBLE, in meters

Retuen value

Returns a circle on the Earth's spherical surface, of type GeoCircle. Its WKT representation is CIRCLE ((<center_lng> <center_lat>), ), which contains the center coordinates and radius information.

ST_CIRCLE has the following edge cases:

• If any input parameter is NULL, returns NULL.
• If <center_lng> is out of [-180, 180] or <center_lat> is out of [-90, 90], returns NULL.
• If is 0, returns a special circle with the center as the only point (WKT representation: CIRCLE ((<center_lng> <center_lat>), 0)).

Example

Basic usage (normal circle)

SELECT ST_AsText(ST_Circle(111, 64, 10000));

+--------------------------------------------+
| st_astext(st_circle(111.0, 64.0, 10000.0)) |
+--------------------------------------------+
| CIRCLE ((111 64), 10000)                   |
+--------------------------------------------+

Circle on the equator (latitude 0°)

mysql> SELECT ST_AsText(ST_Circle(0, 0, 5000));
+----------------------------------+
| ST_AsText(ST_Circle(0, 0, 5000)) |
+----------------------------------+
| CIRCLE ((0 0), 5000)             |
+----------------------------------+

Circle with radius 0 (degenerates to a point)

mysql> SELECT ST_AsText(ST_Circle(120, 30, 0));
+----------------------------------+
| ST_AsText(ST_Circle(120, 30, 0)) |
+----------------------------------+
| CIRCLE ((120 30), 0)             |
+----------------------------------+

Invalid parameter (longitude out of range)

mysql> SELECT ST_AsText(ST_Circle(190, 30, 1000));
+-------------------------------------+
| ST_AsText(ST_Circle(190, 30, 1000)) |
+-------------------------------------+
| NULL                                |
+-------------------------------------+

NULL parameter

mysql> SELECT ST_AsText(ST_Circle(NULL, 30, 1000));
+--------------------------------------+
| ST_AsText(ST_Circle(NULL, 30, 1000)) |
+--------------------------------------+
| NULL                                 |
+--------------------------------------+