ST_Union method

geometry-expression.ST_Union(geo2)

Name	Type	Description
geo2	ST_Geometry	The other geometry value that is to be unioned with the geometry-expression.

ST_Geometry Returns the geometry value that represents the point set union of two geometries.
The spatial reference system identifier of the result is the same as the spatial reference system of the geometry-expression.

The ST_Union method finds the spatial union of two geometries. A point is included in the union if it is present in either of the two input geometries.

Note

If the geometry-expression contains circularstrings, then these are interpolated to line strings.

SQL/MM (ISO/IEC 13249-3: 2006) 5.1.19

The following example shows the union (C) of a square (A) and a circle (B).

SELECT NEW ST_Polygon( 'Polygon( (-1 -0.25, 1 -0.25, 1 2.25, -1 2.25, -1 -0.25) )' ) AS A
    , NEW ST_CurvePolygon( 'CurvePolygon( CircularString( 0 1, 1 2, 2 1, 1 0, 0 1 ) )' )  AS B
    , A.ST_Union( B ) AS C

The union is shaded in the following picture. The union is a single surface that includes all of the points that are in A or in B.

ST_Union method

Syntax

Parameters

Returns

Remarks

Note

See also

Standards and compatibility

Example