Question

I will like to understand the most efficient way to achieve this:

I have a MySQL table with my users info, including birthday (YYYY/MM/DD). My objective is to retrieve an array (php) with the total of user for each individual age from 10 to 60 years old. I can just query all my users, pass the birthday to a birthday to age php function I wrote and then populate an array with the totals. But I wonder if there’s a way to build an sql query that does this job for me?

Answer 1

You should be able to group the rows:

SELECT
    FLOOR(DATEDIFF(NOW(), `birthday`)/365) AS 'Age',
    COUNT(*)
FROM `users`
WHERE FLOOR(DATEDIFF(NOW(), `birthday`)/365) BETWEEN 10 AND 60
AND `id` IN (1, 3, 5, 12, 29)
GROUP BY FLOOR(DATEDIFF(NOW(), `birthday`)/365)
ORDER BY FLOOR(DATEDIFF(NOW(), `birthday`)/365) ASC

The result won’t contain ages that have no users, but I’m not sure why you’d need that.

Updates
– Added an id filter
– Fixed the date calculation (oops!)
– Named the new column