| <!-- |
| Licensed to the Apache Software Foundation (ASF) under one |
| or more contributor license agreements. See the NOTICE file |
| distributed with this work for additional information |
| regarding copyright ownership. The ASF licenses this file |
| to you under the Apache License, Version 2.0 (the |
| "License"); you may not use this file except in compliance |
| with the License. You may obtain a copy of the License at |
| |
| http://www.apache.org/licenses/LICENSE-2.0 |
| |
| Unless required by applicable law or agreed to in writing, |
| software distributed under the License is distributed on an |
| "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| KIND, either express or implied. See the License for the |
| specific language governing permissions and limitations |
| under the License. |
| --> |
| |
| # ST_Union |
| |
| Introduction: |
| |
| Variant 1: Return the union of geometry A and B. |
| |
| Variant 2 : As of version `1.6.0`, this function accepts an array of Geometry objects and returns the geometric union of all geometries in the input array. If the polygons within the input array do not share common boundaries, the ST_Union result will be a MultiPolygon geometry. |
| |
|  |
| |
| Format: |
| |
| `ST_Union (A: Geometry, B: Geometry)` |
| |
| `ST_Union (geoms: Array(Geometry))` |
| |
| Return type: `Geometry` |
| |
| Since: `v1.2.0` |
| |
| SQL Example |
| |
| ```sql |
| SELECT ST_Union(ST_GeomFromWKT('POLYGON ((-3 -3, 3 -3, 3 3, -3 3, -3 -3))'), ST_GeomFromWKT('POLYGON ((1 -2, 5 0, 1 2, 1 -2))')) |
| ``` |
| |
| Output: |
| |
| ``` |
| POLYGON ((3 -1, 3 -3, -3 -3, -3 3, 3 3, 3 1, 5 0, 3 -1)) |
| ``` |
| |
| SQL Example |
| |
| ```sql |
| SELECT ST_Union( |
| Array( |
| ST_GeomFromWKT('POLYGON ((-3 -3, 3 -3, 3 3, -3 3, -3 -3))'), |
| ST_GeomFromWKT('POLYGON ((-2 1, 2 1, 2 4, -2 4, -2 1))') |
| ) |
| ) |
| ``` |
| |
| Output: |
| |
| ``` |
| POLYGON ((2 3, 3 3, 3 -3, -3 -3, -3 3, -2 3, -2 4, 2 4, 2 3)) |
| ``` |
