WITH MyTable AS ( 
    SELECT
        TOTAL_VALUE as x
    FROM
        CONVENIENCE 
    WHERE
        SURVEY_YEAR = 2019 and
        KIND_CODE = '100'
) 
SELECT round(AVG(x)) as SA_MEDIAN
FROM (SELECT x
      FROM MyTable
      ORDER BY x
      LIMIT 2 - (SELECT COUNT(*) FROM MyTable) % 2    -- odd 1, even 2
      OFFSET (SELECT (COUNT(*) - 1) / 2
              FROM MyTable))