Question

I have a simple MySQL table like this:

create table `users`( 
   `id` int(5) NOT NULL AUTO_INCREMENT , 
   `user` varchar(100) NOT NULL , 
   `registration_date` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP , 
   PRIMARY KEY (`id`)
 )

and I’m wondering how should I get the count of users that have been registered:

• today
• this week
• this month

and is there any way of doing this in a single query ?

Answer 1

Assuming Monday is the start of the week, use:

SELECT SUM(CASE 
             WHEN FROM_UNIXTIME(u.registration_date, '%Y-%m-%d') = CURDATE() THEN 1 
             ELSE 0 
           END) AS numToday,
       SUM(CASE 
             WHEN FROM_UNIXTIME(u.registration_date, '%Y-%m-%d') BETWEEN DATE_ADD(CURDATE(), INTERVAL 0-WEEKDAY(CURDATE()) DAY)AND CURDATE() THEN 1 
             ELSE 0 
           END) AS numThisWeek,
       SUM(CASE 
             WHEN FROM_UNIXTIME(u.registration_date, '%Y-%m') = DATE_FORMAT(NOW(), '%Y-%m') THEN 1 
             ELSE 0 
           END) AS numThisMonth
  FROM USERS u

Though, because of using FROM_UNIXTIME this won’t be able to use an index if one existed on the registration_date column. You could though, if you reversed the logic to apply the UNIX_TIMESTAMP function to the values for the dates being filtered against.