MySQL:

WITH numbered AS (
    SELECT 
        lat_n,
        ROW_NUMBER() OVER(ORDER BY lat_n ASC) AS index_row,
        COUNT(*) OVER () AS total_rows
    FROM station
)   

SELECT
    ROUND(AVG(lat_n), 4) AS mediana
FROM numbered
WHERE index_row IN (
    FLOOR((total_rows + 1) / 2),
    CEIL((total_rows + 1) / 2)
);

Running code in MySQL

WITH Ordered AS ( SELECT LAT_N, ROW_NUMBER() OVER (ORDER BY LAT_N) AS rn, COUNT(*) OVER () AS total FROM STATION ) SELECT ROUND(AVG(LAT_N), 4) AS median_lat_n FROM Ordered WHERE rn IN ((total + 1) / 2, (total + 2) / 2);

with cte as( SELECT LAT_N, ROW_NUMBER()OVER(Order By ROUND(LAT_N,4) ASC) rn FROM STATION ) , ctern as( Select Floor(MAX(rn)/2) as marn,ceiling(MAX(rn)/2) as mirn,Count(*) co From cte ) Select round(Avg(LAT_N),4) from cte WHERE 1= Case when Round(MOD(rn,2))=0 AND rn = (Select marn from ctern) or rn = (Select mirn from ctern) then 1 WHEN Round(MOD(rn,2))=1 AND rn = (Select mirn from ctern) then 1 Else 0 END

select round(LAT_N,4) from (select LAT_N from STATION order by LAT_N limit 250) as new_table order by LAT_N desc limit 1

WITH RankedData AS ( SELECT LAT_N, ROW_NUMBER() OVER (ORDER BY LAT_N) AS rn, COUNT(*) OVER () AS total_rows FROM station ) SELECT ROUND(AVG(LAT_N),4) as MEDIAN FROM RankedData WHERE rn in (FLOOR((total_rows+1)/2), CEIL((total_rows + 1) / 2))

-- floor makes 4.5 to 4 -- and ceil makes 4.5 to 5