--select  nom, salaire, commision, (salaire+commision) from employe where fonction='Vendeur';
--select nom, prenom from employe where fonction='Vendeur' order by (nom) desc;
--select fonction,nom from employe order by fonction,nom;
--select nom, prenom, salaire from employe where commision < (salaire/4);
--select count(*) from employe where serno=10;
select count(*) from employe where commision is not NULL and commision >0;
