-- Query 25: same as query 13, but using a subrequest

SELECT
    srv2.numserveur,
    srv2.nomserveur,
    srv2.villeserveur
FROM serveur srv2
WHERE
    srv2.villeserveur IN (
        SELECT srv1.villeserveur
        FROM serveur srv1
        WHERE srv1.nomserveur = "Durant Pierre"
    )
    AND srv2.nomserveur != "Durant Pierre";

/* == RESULT ==
"numserveur","nomserveur","villeserveur"
53,"Pillot Alain","BELFORT"
*/