MySQL - Compare each field with the rest of the database

i'm getting crazy trying to figure this out with pure MySQL and no PHP.

I want to select rows on开发者_如何学Cly if the comparition of that row with the rest of the database gives certain number which is not important.

The thing im trying to achieve is something like this:

SELECT * FROM table WHERE field > ( SELECT f FROM table WHERE date < XXX )

I'm assuming that the query in brackets does not return a single value (because date < XXX indicates more values with respect to time). So...

I think what you need to try and do is form a relationship between table2 and table1 so that you can make a per-row field cell comparison.

E.g.

SELECT * FROM table1 t1 
INNER JOIN (SELECT f FROM table2 WHERE data < xxx) t2 
ON t1.foo = t2.bar
WHERE t1.field > t2.f

I suspect what you want is a combination of group, count, and having. For exampleif you wanted to find all users who have made more than 10 posts since a certain date, you could do

SELECT *, COUNT(posts.id) as pcount 
from users 
left join posts on (posts.user = users.id AND post_made > ZZZ)  
HAVING COUNT(posts.id) > 10

The having clause lets you use aggregate fields like in a where clause.