Question

I have a database driven community web site, where users can post entries. Each entry has a date. Now I’d like to know who was the first user who had an entry count of 1000. Is this possible with a SQL query or do I have to do that programatically, counting each post until the limit is reached? Or any other solutions?

Answer 1

create table posts (
id int not null auto_increment primary key,
user_id int,
post_date date
) engine = myisam;


insert into posts (user_id,post_date)
values 
(1,'2011-03-02'),
(1,'2011-04-10'),
(1,'2011-11-13'),
(2,'2011-03-02'),
(2,'2011-03-02'),
(3,'2011-01-01'),
(3,'2011-01-02'),
(3,'2011-01-03');


select * from (
select posts.*,
   @num := if(@user_id = user_id, @num + 1, 1) as rownum,
   @user_id:=user_id as uid
from posts,(select @user_id := 0, @num := 1) as t
order by user_id asc, post_date asc) 
as tab 
where rownum = 3
order by post_date limit 1

This is an example where I find first user who reaches 3 messages. Hope it helps you.