SELECT DISTINCT U.USR_USERNAME USERNAME, C.CON_VALUE GROUP_NAME FROM (USERS U LEFT JOIN GROUP_USER GU
  ON U.USR_UID=GU.USR_UID) LEFT JOIN CONTENT C
  ON GU.GRP_UID=C.CON_ID
  WHERE U.USR_STATUS='ACTIVE' AND C.CON_VALUE IS NOT NULL
  ORDER BY C.CON_VALUE