SELECT * FROM c_info WHERE f_cityid IN ( SELECT f_id FROM c_city WHERE f_parent = 2 AND f_level = 2 ) AND f_status = 1 AND f_new=0 ORDER BY f_date DESC LIMIT 0,10
SELECT * FROM c_info WHERE f_cityid IN ( SELECT f_id FROM c_city WHERE f_parent = 2 AND f_level = 2 ) AND f_status = 1 AND f_new=0 ORDER BY f_date DESC LIMIT 0,10
SELECT * FROM c_info a WHERE f_status = 1 AND f_new=0 and exists (SELECT 1 FROM c_city where f_parent = 2
AND f_level = 2 and a.f_cityid = f_id )
ORDER BY f_date DESC LIMIT 0,10