I'm trying to use python language in postgresql. Something like this:

create or replace function test(_a integer) returns integer as $$

if _a%2==0:
    return 'even'
elif _a%3==0:
    return 'mult of 3'

else:
    return _a

$$ language plpython3u

But when I run this, I get this error:

ERROR:  language "plpython3u" does not exist
HINT:  Use CREATE EXTENSION to load the language into the database.
SQL state: 42704

Then, I tried to create the extension of the python language by executing:

create extension plpython3u

Which tells me the following error:

ERROR:  could not load library "C:/Program Files/PostgreSQL/12/lib/plpython3.dll": The specified module could not be found.

SQL state: 58P01

I checked if the plpython3.dll file is there. Then I read something about modifying the postgresql configure file by compiling postgres from the source code and adding --with python (I found some of this here).

My problem is that I don't know how to actually do this. My OS is windows server 2019 64 bits, python version is 3.7.4 and postgresql version is 12.2-1 (pgadmin 4.18).

How can I solve this?