ST_M

ST_M returns the m coordinate of an input point.

Syntax

ST_M(point)

Arguments

point

A POINT value of data type GEOMETRY.

Return type

DOUBLE PRECISION value of the m coordinate.

If point is null, then null is returned.

If point is a 2D or 3DZ point, then null is returned.

If point is the empty point, then null is returned.

If point is not a POINT, then an error is returned.

Examples

The following SQL returns the m coordinate of a point in a 3DM geometry.

SELECT ST_M(ST_GeomFromEWKT('POINT M (1 2 3)'));

st_m
-----------
 3                

The following SQL returns the m coordinate of a point in a 4D geometry.

SELECT ST_M(ST_GeomFromEWKT('POINT ZM (1 2 3 4)'));

st_m
-----------
 4