mysql - 迭代计数和 where 子句

Question

我需要一些帮助。我有很多用户及其出生日期:

SELECT COUNT(or SUM) ()    FROM ()

WHERE () = ''  

AND TIMESTAMPDIFF(YEAR, date_of_birth, CURDATE())=18(age)

我必须通过仅更改 where 子句中的年龄来多次计算列的计数、总和、平均值等。如何确保我不会浪费时间多次运行查询？我必须从 18 岁升至 65 岁:

SELECT COUNT(or SUM) () FROM ()

WHERE () = ''  AND () = ''

AND ()<'' 

AND TIMESTAMPDIFF(YEAR, date_of_birth, CURDATE())=**19,29,21 etc**.

I would like this columns results:

count()  18

count()  19 etc

or

sum () 18

sum() 19 etc 

真的非常感谢。

Answer 1

将TIMESTAMPDIFF的结果作为列返回，然后使用GROUP BY。

SELECT TIMESTAMPDIFF(YEAR, date_of_birth, CURDATE()) AS age, COUNT(*)
FROM ...
WHERE ...
GROUP BY age