SELECT ROUND(AVG(TOTAL_VALUE)) AS SA_MEDIAN FROM 

(SELECT TOTAL_VALUE FROM CONVENIENCE
WHERE SURVEY_YEAR = 2019 AND KIND_CODE = '100'
ORDER BY TOTAL_VALUE
LIMIT 2 - (SELECT COUNT(*) 
FROM (
SELECT TOTAL_VALUE FROM CONVENIENCE
WHERE SURVEY_YEAR = 2019 AND KIND_CODE = '100'
)
) % 2    -- odd 1, even 2
  OFFSET (SELECT (COUNT(*) - 1) / 2
  FROM (
  SELECT TOTAL_VALUE FROM CONVENIENCE
  WHERE SURVEY_YEAR = 2019 AND KIND_CODE = '100')
))