sql - Mysql - get results from complex criteria -

i have database statistics on number of websites , i'm having issue rather complex query have no idea how (or if it's possible).

i have 2 tables: websites , visits. former list of websites , properties, while former list of each user's visit on specific website.

the program i'm making supposed fetch websites need "scanned". interval between each scan each site depends on websites total number of visits last 30 days. here table intended scan-interval:

the tables have following structure:

websites

visits

what want query returns websites either at or past individual update deadline (can seen last_scanned column).

is doable in single query?

here's can try:

select main.*  (    select     w.web_id,     w.url,     w.last_scanned,     (select count(*)      visits v      v.web_id = w.web_id        , timestampdiff(day,v.added_on, now()) <=30     ) visit_count,     timestampdiff(hour,w.last_scanned, now()) hrs_since_update   websites w   ) main   (case      when visit_count >= 0 , visit_count <= 10 , hrs_since_update >= 4320 1     when visit_count >= 11 , visit_count <= 100 , hrs_since_update >= 2160 1     when visit_count >= 101 , visit_count <= 500 , hrs_since_update >= 1080 1     when visit_count >= 501 , visit_count <= 1000 , hrs_since_update >= 720 1     when visit_count >= 1001 , visit_count <= 2000 , hrs_since_update >= 360 1     when visit_count >= 2001 , visit_count <= 5000 , hrs_since_update >= 168 1     when visit_count >= 5001 , visit_count <= 10000 , hrs_since_update >= 72 1     when visit_count >= 10001 , hrs_since_update >= 24 1     else 0    end) = 1; 

here's fiddle demo: http://sqlfiddle.com/#!9/1f671/1