/* WHEN NAME is AAA AND the ENDTIME is NULL, replace with system date (date and time now) */

SELECT
 ID,
 NAME,
 START_TIME
 CASE
   WHEN NAME = 'AAA' AND ENDTIME IS NULL THEN SYSDATE
   ELSE ENDTIME
 END AS ENDTIME
FROM
(
SELECT
  ID,
  Name,
  MAX(Start_Time) AS STARTTIME,
  End_Time        AS ENDTIME
FROM
  chamber
GROUP BY
  Name
) a
/