[GIS] Convert geometry to latitude-longitude using PostGIS ST_Transform

coordinate systemcoordinatespostgis

My table has a geometric field, in EPSG:3857, of type point. I need the latitude and longitude, in EPSG: 4326, of each point. Could someone give me a valid example of how to use ST_Transform().

Best Answer

From the PostGIS docs,

ST_Transform — Returns a new geometry with its coordinates transformed to the SRID referenced by the integer parameter.

geometry ST_Transform (geometry g, integer srid);

So, to read transformed points

SELECT ST_AsText (ST_Transform (geom, 4326)) FROM table ...

If you want long and lat as separate fields

SELECT ST_X (ST_Transform (geom, 4326)) AS long,
       ST_Y (ST_Transform (geom, 4326)) AS lat
FROM table ...
Related Question