-- SELECT AVG(TOTAL_VALUE)
-- FROM (SELECT PF_CODE,TOTAL_VALUE
--       FROM CONVENIENCE
--       where PF_CODE = "100" and SURVEY_YEAR = "2019"
--       ORDER BY TOTAL_VALUE
--       LIMIT 2 - (SELECT COUNT(*) FROM CONVENIENCE) % 2    -- odd 1, even 2
--       OFFSET (SELECT (COUNT(*) - 1) / 2
--               FROM CONVENIENCE))
SELECT AVG(TOTAL_VALUE)
FROM
(SELECT TOTAL_VALUE
FROM CONVENIENCE
where KIND_CODE = "100" and SURVEY_YEAR = "2019"
ORDER BY TOTAL_VALUE
      LIMIT 2 - (SELECT COUNT(*) FROM CONVENIENCE) % 2    -- odd 1, even 2
      OFFSET (SELECT (COUNT(*) - 1) / 2
              FROM CONVENIENCE))