Question

我在计算MySQL用户的年龄，我遇到了一个小问题。我能够成功计算每个用户的年龄，但是，当我尝试计算每个年龄组的用户数时，就是我遇到麻烦的时候。这是我的疑问：

  SELECT COUNT(user_id) AS "Number of Users", 
           YEAR(CURDATE()) - 
           YEAR(STR_TO_DATE(birth_date, '%m/%d/%Y')) - 
           (RIGHT(CURDATE(), 5) < RIGHT(STR_TO_DATE(birth_date, '%m/%d/%Y'), 5)) 
             AS Age
    FROM user 
GROUP BY Age

我觉得我很亲密，只是不适合我。我如何计算每个年龄段的用户数量？

Answer 1

您需要一个子查询来访问Group By子句

中计算的列别名Age

SELECT Age,COUNT(user_id) AS "Number of Users"

FROM
(
    SELECT userid,
           YEAR(CURDATE()) - 
           YEAR(STR_TO_DATE(birth_date, '%m/%d/%Y')) - 
           (RIGHT(CURDATE(), 5) < RIGHT(STR_TO_DATE(birth_date, '%m/%d/%Y'), 5)) 
             AS Age
    FROM user
) as Z 
GROUP BY Age

MySQL查询计算年龄组中的用户数

1 个答案: