ST_MakePolygon-PolarDB(PolarDB)-阿里云帮助中心

Constructs a polygon from a closed LineString that defines the exterior ring, with an optional array of closed LineStrings that define interior rings (holes).

Syntax

geometry ST_MakePolygon(geometry linestring);
geometry ST_MakePolygon(geometry outerlinestring, geometry[] interiorlinestrings);

Parameters

Parameter	Description
`linestring`	The closed LineString that defines the exterior ring of the polygon.
`outerlinestring`	The closed LineString that defines the exterior ring of the polygon.
`interiorlinestrings`	An array of closed LineStrings, each defining an interior ring (hole) of the polygon.

Usage notes

Both linestring and each element of interiorlinestrings must be a closed LineString — the start and end points must be identical.

Examples

Construct a polygon from a single closed LineString:

SELECT ST_AsText(ST_MakePolygon(ST_GeomFromText('LINESTRING(1 2,3 4,5 6,1 2)')));
         st_astext
----------------------------
 POLYGON((1 2,3 4,5 6,1 2))
(1 row)

Construct a polygon with an interior ring:

SELECT ST_AsText(ST_MakePolygon(ST_GeomFromText('LINESTRING(0 0,0 1,1 1,0 0)'),ARRAY[ST_GeomFromText('LINESTRING(-1 -1,-1 2,2 2,-1 -1)')]));
                     st_astext
---------------------------------------------------
 POLYGON((0 0,0 1,1 1,0 0),(-1 -1,-1 2,2 2,-1 -1))
(1 row)