Postgres - SQL Recursivity to get the highest parent

I need some help to create an SQL query with recursivity (POSTGRES). Let's explain.

This is a part of my table named "employe".

id string
nom string
manager string (reference the column id)

and this is a snapshot this is a snapshot of table "employe"

what I want is to extract for each "employe" the highest manager in the hierarchy.

Im trying to do it by using recursivity. This is what i try :

WITH    RECURSIVE q AS
        (
        SELECT  m
        FROM    employe m
        WHERE   id = '9'
        UNION ALL
        SELECT  m
        FROM    q
        JOIN    employe m
        ON      m.id = q.manager
        )
SELECT  (m).*
FROM    q
WHERE   (m).manager IS NULL

But it's not working...

It's an example of what i try to do :

Anyone can help me ? Thanks in advance.

You can combine a recursive CTE with the DISTINCT ON clause to get the highest parent, as in:

with recursive
n as (
  select id, nom, manager, 0 as lvl from employee
 union all
  select n.id, n.nom, m.manager, n.lvl + 1
  from n
  join employee m on m.id = n.manager and m.manager is not null
)
select distinct on (id) * 
from n
order by id, lvl desc

Result:

 id  nom        manager  lvl 
 --- ---------- -------- --- 
 1   MARTIN     null     0   
 2   DURANT     1        0   
 3   MARQUET    1        1   
 4   BEN HARFA  null     0   
 5   CASTEL     4        0   
 6   CALISKAN   null     0   
 7   BISSON     6        0   
 8   VERRATI    6        1   
 9   BALUZO     6        2   
 10  ROUSSET    null     0   

See running example at db<>fiddle.