>WHEN Client.NoCompany>0 THEN
>
>case when  (SELECT top (1) Company.Activated FROM Company WHERE Company.Numero=Client.NoCompany)=1 then 2
>else 3 end
>end

UPDATE Client
 SET NoType=
  CASE
  WHEN Client.NoCompany=0 AND Client.NoProvince>0 THEN 1
  WHEN Client.NoCompany>0 THEN
   CASE WHEN EXISTS (SELECT Company.Numero FROM Company WHERE Company.Numero=Client.NoCompany AND Company.Activated=0) THEN 2
   ELSE 3
   END
  END