Set 2 colums after an update on a table

i am infamiliar wth your rdms but sure it osn’t MySQL, you should change that

But when your first update worked, yu can use the following.

CREATE or ALTER TRIGGER majVilleClient
on client
instead of insert
as
begin
update client
set nom_client =upper(nom_client)
,nom_ville = upper(nom_ville)
where nom_client in (select nom_client from inserted)

end