PG V9.6 / REVOKE SELECT columns ON TABLE T1 FROM John

Hello,

I 've created a PostgreSQL user "John" with REVOKE SELECT columns from him.
but "REVOKE SELECT (ipp , nom_nais , nom , prenom) ON TABLE table1 FROM "John";" command doesn't work in my script above :

Here is how I created the user "John":

CREATE ROLE "john";
REVOKE ALL PRIVILEGES ON DATABASE pgdb FROM "john";
ALTER ROLE "john" WITH LOGIN;
ALTER ROLE "john" WITH PASSWORD 'password' VALID UNTIL '2018-12-31';
GRANT CONNECT ON DATABASE dbpg TO "john";
GRANT USAGE ON SCHEMA schema1 TO "john";
----- forbid access to 4 columns of Table1
REVOKE SELECT (ipp , nom_nais , nom , prenom) ON TABLE Table1 FROM "John";

Result :
The 4 columns are still displayed.
The "REVOKE SELECT column" doen't work. I manage always to select values in the 4 columns.

Can you see why John can still watch the 4 columns ?
Is a comand missing in this script ?
Database version is 9.6.

Thanks a lot for your help !

Etienne DECHERF
DBA
etienne(dot)decherf-ext(at)aphp(dot)fr
+33 6 67462246