WITH t AS (
    SELECT TOTAL_VALUE AS v FROM CONVENIENCE WHERE SURVEY_YEAR = 2019 AND KIND_CODE = '100' ORDER BY v
)
, u AS (
    SELECT COUNT(0) AS c FROM t
)

SELECT
    ROUND(
        ((SELECT MAX(v) FROM (SELECT v FROM t LIMIT (SELECT ROUND(c * 0.5) FROM u)))
        + (SELECT MAX(v) FROM (SELECT v FROM t LIMIT (SELECT ROUND(c * 0.5 + 0.5) FROM u))))
        * 0.5
    ) AS SA_MEDIAN
;