獲取用戶表mysql的平均男性和女性

Question

如何編寫查詢以從用戶表中獲得總用戶％女性％男性。我有一個用戶表，其中有男性和女性的列。

Answer 1

mysql> CREATE TABLE user (username VARCHAR(20) NOT NULL, gender ENUM('male','female')); 
Query OK, 0 rows affected (0.09 sec) 

mysql> INSERT INTO user (username, gender) VALUES 
    -> ('berry', 'male'), 
    -> ('jessica alba', 'female'), 
    -> ('Sasha DiGiulian', 'female'); 
Query OK, 3 rows affected (0.03 sec) 
Records: 3 Duplicates: 0 Warnings: 0 

mysql> SELECT COUNT(username), gender FROM user GROUP BY gender; 
+-----------------+--------+ 
| COUNT(username) | gender | 
+-----------------+--------+ 
|    1 | male | 
|    2 | female | 
+-----------------+--------+ 
2 rows in set (0.02 sec) 


mysql> SELECT total, gender, number, (100 * number/total) AS percentage FROM (SELECT COUNT(username) AS total FROM user) AS total, (SELECT COUNT(username) AS number, gender FROM user GROUP BY gender) as genders; 
+-------+--------+--------+------------+ 
| total | gender | number | percentage | 
+-------+--------+--------+------------+ 
|  3 | male |  1 | 33.3333 | 
|  3 | female |  2 | 66.6667 | 
+-------+--------+--------+------------+ 
2 rows in set (0.00 sec) 

編輯：增加了百分比的計算。

Answer 2

有沒有真正足夠的具體信息去，因此它必須是僞代碼，恐怕：

%male = (100 * Number of Rows where sex == Male)/Total Number of Rows 
%female = (100 * Number of Rows where sex == Female)/Total Number of Rows 

如果每行只能是男性或女性，女性百分比= 100 - ％男性。