SELECT t1.* 
FROM ads t1
JOIN city t2 ON t1.city_id=t2.id
JOIN city_group t3 ON t1.city_id=t3.bottom_level
WHERE t1.info=0 AND t3.top_level = '358'  
ORDER BY t1.time DESC LIMIT 100

CREATE TABLE IF NOT EXISTS `ads` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `title` varchar(255) DEFAULT NULL,
  `description` text,
  `category_id` int(11) NOT NULL DEFAULT '0',
  `city_id` int(11) DEFAULT '0',
  `adress` varchar(255) DEFAULT NULL,
  `phone` varchar(255) DEFAULT NULL,
  `email` varchar(255) DEFAULT NULL,
  `name` varchar(255) DEFAULT NULL,
  `pass` varchar(16) DEFAULT NULL,
  `time` int(11) DEFAULT NULL,
  `info` int(1) DEFAULT '1',
  PRIMARY KEY (`id`),
  KEY `category_id` (`category_id`),
  KEY `city_id` (`city_id`),
  KEY `info` (`info`),
  FULLTEXT KEY `title` (`title`,`description`)
) ENGINE=MyISAM  DEFAULT CHARSET=cp1251 AUTO_INCREMENT=1;

CREATE TABLE IF NOT EXISTS `city` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `city_name` varchar(255) DEFAULT NULL,
  `city_filename` varchar(255) DEFAULT NULL,
  `parent_city_id` int(11) NOT NULL DEFAULT '0',
  PRIMARY KEY (`id`),
  UNIQUE KEY `city_filename` (`city_filename`),
  KEY `city_name` (`city_name`),
  KEY `parent_city_id` (`parent_city_id`)
) ENGINE=MyISAM  DEFAULT CHARSET=cp1251 AUTO_INCREMENT=1;

CREATE TABLE IF NOT EXISTS `city_group` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `top_level` int(11) NOT NULL,
  `bottom_level` int(11) NOT NULL,
  PRIMARY KEY (`id`),
  KEY `top_level` (`top_level`,`bottom_level`)
) ENGINE=MyISAM  DEFAULT CHARSET=cp1251 AUTO_INCREMENT=1;