Query min value

USE tempdb;

CREATE TABLE dbo.foo(
nome varchar(10) NOT NULL,
numeroAttivita int NOT NULL
);

INSERT dbo.foo
VALUES ('pippo', 3)
     , ('pluto', 7)
     , ('alex', 1);

WITH CTE_GetMinActivities(ActivitiesNo) AS
(
    SELECT MIN(numeroAttivita)
    FROM dbo.foo
)    
SELECT F.*
FROM dbo.foo AS F
JOIN CTE_GetMinActivities AS A
ON F.numeroAttivita = A.ActivitiesNo;

/* Output:

nome       numeroAttivita
---------- --------------
alex       1

(1 row(s) affected)

*/

DROP TABLE dbo.foo;

WITH CTE_Users(Utente, NumeroAttivita) AS
(
    SELECT U1.Utente, COUNT(*)
    FROM dbo.tabellaUtente AS U1
    JOIN dbo.Utenti AS U2
    ON U1.Utente = U2.Utente
    WHERE U2.Ruolo = 'dipendente'
    GROUP BY U1.Utente 
),
CTE_GetMinActivities(ActivitiesNo) AS
(
    SELECT MIN(NumeroAttivita)
    FROM CTE_Users
)
SELECT U.*
FROM CTE_Users AS U
JOIN CTE_GetMinActivities AS A
ON U.NumeroAttivita = A.ActivitiesNo;