ST_UnionAggr method for type ST

ST_Geometry::ST_UnionAggr(geometry-column)

Name	Type	Description
geometry-column	ST_Geometry	The geometry values to generate the spatial union. Typically this is a column.

ST_Geometry Returns a geometry that is the spatial union for all the geometries in a group.
The spatial reference system identifier of the result is the same as that for the first parameter.

Rows where the argument is NULL are not included.

Returns NULL for an empty group or a group containing no non-NULL values.

If the group contains a single non-NULL geometry, it is returned. Otherwise, the union is logically computed by repeatedly applying the ST_Union method to combine two geometries at a time. See ST_Union method for type ST_Geometry.

ST_Union method for type ST_Geometry

SQL/MM (ISO/IEC 13249-3: 2006) Vendor extension

The following example returns the result Polygon ((.555555 3, 0 3, 0 1.75, 0 0, 3 0, 3 3, .75 3, 1 4, .555555 3)).

SELECT ST_Geometry::ST_UnionAggr( Shape ) 
FROM SpatialShapes WHERE ShapeID IN ( 2, 6 )

ST_UnionAggr method for type ST_Geometry

Syntax

Parameters

Returns

Remarks

See also

Standards and compatibility

Example