ST_Y

Description

Returns the Y coordinate of a valid POINT geometry. In geospatial contexts, the Y coordinate typically corresponds to Latitude, ranging from [-90.0, 90.0] (in degrees).

Sytax

ST_Y( <point>)

Parameters

Parameters	Description
<point>	A valid 2D POINT geometry from which to extract the Y coordinate. The Y value (latitude) must be within [-90.0, 90.0], and the X value (longitude) must be within [-180.0, 180.0].

Retuen value

The Y coordinate of the input POINT, returned as a DOUBLE PRECISION FLOAT.

Returns the Y coordinate (latitude) for valid POINT inputs. Returns NULL for NULL inputs, empty points (POINT EMPTY), 3D points, or invalid points (e.g., latitude outside [-90.0, 90.0]).

Examples

Valid Point

SELECT ST_Y(ST_Point(24.7, 56.7));

+----------------------------+
| ST_Y(ST_Point(24.7, 56.7)) |
+----------------------------+
| 56.7                       |
+----------------------------+

Empty Point (POINT EMPTY)

mysql> SELECT ST_Y(ST_GeometryFromText("POINT EMPTY"));
+------------------------------------------+
| ST_Y(ST_GeometryFromText("POINT EMPTY")) |
+------------------------------------------+
|                                     NULL |
+------------------------------------------+

3D Point (Not Supported)

mysql> SELECT ST_Y(ST_GeometryFromText("POINT (10 20 30)"));
+-----------------------------------------------+
| ST_Y(ST_GeometryFromText("POINT (10 20 30)")) |
+-----------------------------------------------+
|                                          NULL |
+-----------------------------------------------+

NULL Input

mysql> SELECT ST_Y(NULL);
+------------+
| ST_Y(NULL) |
+------------+
|       NULL |
+------------+

Invalid Latitude (Out of Range)

mysql> SELECT ST_Y(ST_Point(116.4, 91));
+---------------------------+
| ST_Y(ST_Point(116.4, 91)) |
+---------------------------+
|                      NULL |
+---------------------------+

Invalid Longitude (Out of Range)

mysql> SELECT ST_Y(ST_Point(190, 39.9));
+---------------------------+
| ST_Y(ST_Point(190, 39.9)) |
+---------------------------+
|                      NULL |
+---------------------------+