WITH data AS (
    SELECT TOTAL_VALUE
    FROM CONVENIENCE
    WHERE SURVEY_YEAR = 2019 AND KIND_CODE='100'
)

SELECT ROUND(AVG(TOTAL_VALUE)) AS SA_MEDIAN
FROM (
    SELECT TOTAL_VALUE
    FROM data
    ORDER BY TOTAL_VALUE
    LIMIT 2 - (SELECT COUNT(*) FROM data) % 2    -- odd 1, even 2
    OFFSET (SELECT (COUNT(*) - 1) / 2
            FROM data
            )
)