CREATE DEFINER=`root`@`%` FUNCTION `get_median_from_communityhistoryprice`() RETURNS float

BEGIN

declare return_value float;

declare median int;

declare median2 int;

declare median_even_1 int;

declare median_even_2 int;

declare temp_1 int;

SELECT count(*) into median from communityhistoryprice;

-- 如果是奇数个数量

if median % 2 = 1 then

select FLOOR(median / 2) into median2;

SELECT price into return_value from communityhistoryprice ORDER BY price asc limit median2,1;

-- 如果是偶数个数量

ELSE

select (FLOOR(median / 2) -1) into median2;

select FLOOR(median / 2) into temp_1;

SELECT price into median_even_1 from communityhistoryprice ORDER BY price asc limit median2,1;

SELECT price into median_even_2 from communityhistoryprice ORDER BY price asc limit temp_1,1;

set return_value = (median_even_1 + median_even_2)/2;

END IF;

RETURN return_value;

END