PostgreSQL select query to extract latitude and longitude from a point

Question

What SELECT query should be used to extract latitude and longitude from a point?
I cannot use PostGIS.

Example point (point type value) stored in the database:

   my_point
--------------
(50.850,4.383)

Expected result after executing the query:

  lat  |  lng
---------------
50.850 | 4.383

The query below works fine but it does not look efficient.

SELECT 
    split_part(trim(my_point::text, '()'), ',', 1)::float AS lat, 
    split_part(trim(my_point::text, '()'), ',', 2)::float AS lng
FROM my_table;

Colonnade

Answer 1

Always Read The Fine Manuals

It is possible to access the two component numbers of a point as though the point were an array with indexes 0 and 1. For example, if t.p is a point column then SELECT p[0] FROM t retrieves the X coordinate and UPDATE t SET p1 = ... changes the Y coordinate. In the same way, a value of type box or lseg can be treated as an array of two point values.

Inutility

Thank you, this is exactly what I needed. The funny thing is I already read it before asking this question except the lines below the tables. – Colonnade

Worth noting that extracting it from a literal directly will not work: Select point(25,55)[0]; -- will not work!! You need existing point: with a as (select point(25,55) p) select p[0] from a; -- will work! – Systematic

@Valentin it works with parentheses: SELECT (POINT(25,55))[0]; – Slipsheet

Answer 2

Another option would be:

SELECT 
    ST_X(point) as longitude, 
    ST_Y(point) as latitude
FROM your_table_name

Doer