mysql求中位值函数

SELECT AVG(t1.column_name)
FROM (
    SELECT column_name,
           @rownum := @rownum + 1 AS row_number,
           @total_rows := COUNT(*) OVER ()
    FROM table_name, (SELECT @rownum := 0) r
    ORDER BY column_name
) AS t1, (SELECT @total_rows := (SELECT COUNT(*) FROM table_name)) t2
WHERE t1.row_number IN (FLOOR((@total_rows + 1) / 2), FLOOR((@total_rows + 2) / 2));

WITH cte AS (
    SELECT column_name,
           ROW_NUMBER() OVER (ORDER BY column_name) AS row_num,
           COUNT(*) OVER () AS total_rows
    FROM table_name
)
SELECT AVG(column_name) AS median
FROM cte
WHERE row_num IN (FLOOR((total_rows + 1) / 2), FLOOR((total_rows + 2) / 2));