The ST_Y function takes a point as an
input parameter and returns its Y coordinate. You can optionally indicate
a Y coordinate as input parameter in addition to the point and the
function returns the point itself with its Y coordinate set to the
given value.
If the given point is null or is empty, then null is returned.
This
function can also be called as a method.
Syntax
Parameters
point
A value of type ST_Point for which the Y coordinate is returned
or modified.
y_coordinate
A value of type DOUBLE that represents the new Y coordinate for point.
Return types
DOUBLE, if y_coordinate is not specified
db2gse.ST_Point, if y_coordinate is specified
Examples
Example 1
This example illustrates use of the ST_Y function. Geometries
are created and inserted into the SAMPLE_POINTS table.
SET CURRENT FUNCTION PATH = CURRENT FUNCTION PATH, db2gse
CREATE TABLE sample_points (id INTEGER, geometry ST_Point)
INSERT INTO sample_points (id, geometry)
VALUES (1, ST_Point (2, 3, 32, 5, 1) ),
(2, ST_Point (4, 5, 20, 4, 1) ),
(3, ST_Point (3, 8, 23, 7, 1) )
Example 2
This example finds the Y coordinates of the points in the table.
SELECT id, ST_Y (geometry) Y_COORD
FROM sample_points
Results:
ID Y_COORD
---------- ----------------------
1 +3.00000000000000E+000
2 +5.00000000000000E+000
3 +8.00000000000000E+000
Example 3
This example returns a point with its Y coordinate set to 40.
SELECT id, CAST( ST_AsText( ST_Y (geometry, 40)) AS VARCHAR(60) )
Y_40
FROM sample_points
WHERE id=3
Results:
ID Y_40
-------- -------------------------------------------------------
3 POINT ZM ( 3.00000000 40.00000000 23.00000000 7.00000000)