ST_Collect

Syntax

ST_Collect(g)

Description

ST_Collect is an aggregate function that can also be used as a window function.

Given multiple geometries, returns the aggregation of the distinct geometry arguments. This function also supports the DISTINCT option. If DISTINCT is used, it returns the aggregation of the distinct geometry arguments.

The resulting value type is chosen using the following policy:

• If all arguments are Point values, the result is a MultiPoint value.
• If all arguments are LineString values, the result is a MultiLineString value.
• If all arguments are Polygon values, the result is a MultiPolygon value.
• Otherwise, the result is a GeometryCollection value.

If there are multiple geometry arguments and those arguments are in the same spatial reference system (SRS), the return value is in that SRS. If those arguments are not in the same SRS, an ER_GIS_DIFFERENT_SRIDS_AGGREGATION error occurs.

Examples

Multiple Point geometries aggregated into a MultiPoint geometry:

CREATE OR REPLACE TABLE t1 ( running_number INTEGER NOT NULL
  AUTO_INCREMENT, grouping_condition INTEGER, location GEOMETRY , PRIMARY KEY (
  running_number));

INSERT INTO t1 ( grouping_condition, location ) VALUES
  ( 0,ST_GEOMFROMTEXT('POINT(0 0)',4326)),
  ( 1,ST_GEOMFROMTEXT('POINT(0 0)',4326)),
  ( 0,ST_GEOMFROMTEXT('POINT(1 0)',4326)),
  ( 1,ST_GEOMFROMTEXT('POINT(2 0)',4326)),
  ( 0,ST_GEOMFROMTEXT('POINT(3 0)',4326));

SELECT ST_EQUALS( (SELECT ST_COLLECT( location ) AS t FROM t1), 
  ST_GEOMFROMTEXT('MULTIPOINT(0 0,0 0,1 0,2 0,3 0) ',4326));

See Also

• Geometry Constructors
• ST_AsText