Extensions
Scalar Functions
```sql
-- Transform a geometry from EPSG:4326 to EPSG:3857 (WGS84 to WebMercator)
-- Note that since WGS84 is defined as having a [latitude, longitude] axis order
-- we follow the standard and provide the input geometry using that axis order,
-- but the output will be [easting, northing] because that is what's defined by
-- WebMercator.

SELECT ST_AsText(
ST_Transform(
st_point(52.373123, 4.892360),
'EPSG:4326',
'EPSG:3857'
)
);
----
POINT (544615.0239773799 6867874.103539125)

-- Alternatively, let's say we got our input point from e.g., a GeoJSON file,
-- which uses WGS84 but with [longitude, latitude] axis order. We can use the
-- `always_xy` parameter to force the input geometry to be interpreted as having
-- a [northing, easting] axis order instead, even though the source coordinate
-- reference system definition (WGS84) says otherwise.

SELECT ST_AsText(
ST_Transform(
-- note the axis order is reversed here
st_point(4.892360, 52.373123),
'EPSG:4326',
'EPSG:3857',
always_xy := true
)
);
----
POINT (544615.0239773799 6867874.103539125)
```  
----  
#### ST_Union {#docs:extensions:spatial:functions::st_union}