統計男女生人數--sql

統計男女生人數--sql

傳統方法

-- 男性人口
SELECT pref_name AS 地區,
SUM(population) AS 男
FROM `user`
WHERE u_sex = '1'
GROUP BY pref_name;

-- 女性人口
SELECT pref_name AS 地區,
SUM(population) AS 女
FROM `user`
WHERE u_sex ='2'
GROUP BY pref_name;

CASE表達式

-- 統計 人口數據
SELECT pref_name AS 地區,
--  男性人口
SUM(CASE 	WHEN u_sex='1' THEN population	ELSE	0 END ) AS 男,
--  女性人口
SUM(CASE 	WHEN u_sex='2' THEN population	ELSE	0 END ) AS 女
FROM `user`
GROUP BY pref_name

圖例