MySQL 计算中位数

mysql中位数 奇数取中间的值，偶数取中间两个数的平均值

eg: 12345 中位数4 1234 中位数2.5

SELECT avg(t1.money) as median_val FROM ( 
SELECT @rownum:=@rownum+1 as row_number, d.money 
FROM core_order d, (SELECT @rownum:=0) r 
WHERE 1 
– （条件） 
ORDER BY d.money 
) as t1, 
( 
SELECT count(*) as total_rows 
FROM core_order d 
WHERE 1 
– （条件） 
) as t2 
WHERE 1 
AND t1.row_number in ( floor((total_rows+1)/2), floor((total_rows+2)/2) );