SELECT ROUND(AVG(TOTAL_VALUE)) SA_MEDIAN
FROM (
        SELECT TOTAL_VALUE,
            ROW_NUMBER() over(
                order by TOTAL_VALUE
            ) AS row_n,
            (
                SELECT COUNT(*)
                FROM CONVENIENCE
                WHERE SURVEY_YEAR = 2019
                    AND KIND_CODE = '100'
            ) TOTAL
        FROM CONVENIENCE
        WHERE SURVEY_YEAR = 2019
            AND KIND_CODE = '100'
    )
where row_n between TOTAL / 2.0 and TOTAL / 2.0 + 1