ST_CoordDim-ApsaraDB RDS(RDS)-阿里云帮助中心

Returns the coordinate dimension of a geometry object as an integer.

Syntax

integer ST_CoordDim(geometry geomA);

Parameters

Parameter	Description
`geomA`	The geometry object to evaluate.

Description

ST_CoordDim is an alias for ST_NDims. Both functions return the same result.

Supported geometry types: circular strings, curves, polyhedral surfaces, triangles, triangulated irregular network (TIN) surfaces, and 3D objects.

Examples

The following query runs ST_CoordDim on geometries of different dimensions in a single statement, so you can compare results side by side:

SELECT
  ST_CoordDim('POINT(1 0)')      AS d2,
  ST_CoordDim('POINT(1 0 1)')    AS d3z,
  ST_CoordDim('POINTM(1 0 1)')   AS d3m,
  ST_CoordDim('POINT(1 0 1 1)')  AS d4;

Output:

 d2 | d3z | d3m | d4
----+-----+-----+----
  2 |   3 |   3 |  4
(1 row)

Notice that d3z and d3m both return 3, even though one uses Z coordinates and the other uses M (measure) coordinates.