SELECT DISTINCT P.AREA_CODE, P.PHONE_NO,

      (SELECT COUNT(*)

        FROM PHONE P2

       WHERE P2.PHONE_ID = P.PHONE_ID) AS CNT

  FROM PHONE P             

 WHERE P.AREA_CODE IS NOT NULL

 GROUP BY 1, 2         

HAVING (SELECT COUNT(*)

          FROM PHONE P3

         WHERE P3.PHONE_ID = P.PHONE_ID

           AND P3.AREA_CODE IS NOT NULL) > 1

Dynamic SQL Error SQL error code = -104 Invalid expression in the select list (not contained in either an aggregate function or the GROUP BY clause)