Select items from 3 different tables - mysql

Question

I would like to select items from 3 different tables, I am using UNION, but the number of columns is different, so it returns an error of number of columns, is there any other way using JOIN to get an appreciated result?
SELECT *
FROM `ads` JOIN ad_car
ON ads.id_ads = ad_car.main_ad
WHERE ads_cat = :ads_cat AND
ads.ad_status = :adStatus
UNION
SELECT *
FROM `ads` JOIN ad_vehpro
ON ads.id_ads = ad_vehpro.main_ad
WHERE ads_cat = :ads_cat AND
ads.ad_status = :adStatus
ORDER BY date_renewed
DESC LIMIT 4
EDITED: I add the tables:
CREATE TABLE IF NOT EXISTS `ads` (
`id_ads` int(10) unsigned NOT NULL AUTO_INCREMENT,
`id_profiles_key` varchar(20) NOT NULL,
`id_shops` int(4) NOT NULL DEFAULT '1',
`ads_cat` int(2) NOT NULL COMMENT 'main category: vehicule, immobilier,...',
`ads_scat` int(3) NOT NULL COMMENT 'sous cat: voiture, moto,...',
`form_id` varchar(30) NOT NULL COMMENT 'form key',
`city_id` int(5) NOT NULL,
`district_id` int(5) NOT NULL,
`adtype_id` int(1) NOT NULL DEFAULT '1' COMMENT '1: offre, 2: demande',
`ads_title` varchar(200) NOT NULL,
`ads_description` longtext NOT NULL,
`ads_price` int(11) NOT NULL,
`num_img` int(2) NOT NULL DEFAULT '1' COMMENT 'number of images',
`num_vid` int(2) NOT NULL DEFAULT '0' COMMENT 'number of video',
`num_com` int(3) NOT NULL DEFAULT '0' COMMENT 'number of comments',
`to_pin` int(1) NOT NULL DEFAULT '0' COMMENT 'ad that will be pinned. 0: no, 1: yes',
`date_inserted` varchar(20) NOT NULL,
`date_modified` varchar(20) NOT NULL,
`date_renewed` varchar(20) NOT NULL,
`date_pinned` varchar(20) NOT NULL DEFAULT '0',
`ad_status` int(1) NOT NULL DEFAULT '1' COMMENT '0: not active, 1: active, 2: deleted, 3: pinned',
PRIMARY KEY (`id_ads`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=7 ;
CREATE TABLE IF NOT EXISTS `ad_car` (
`id_ad` int(10) unsigned NOT NULL AUTO_INCREMENT,
`main_ad` int(5) NOT NULL COMMENT 'this will refer to main table ads (id_ads)',
`id_profiles` varchar(20) NOT NULL,
`city_id` int(5) NOT NULL,
`district_id` int(5) NOT NULL COMMENT 'district id from districts table',
`category_id` int(2) NOT NULL,
`make_id` int(5) NOT NULL,
`model_id` int(5) NOT NULL,
`model_year` int(4) NOT NULL,
`engine` int(2) NOT NULL,
`fuel` int(1) NOT NULL,
`mileage` bigint(7) NOT NULL,
`transmission` int(1) NOT NULL,
`wheed_drive` int(1) NOT NULL,
`in_color` varchar(7) NOT NULL,
`ex_color` varchar(7) NOT NULL,
`seats` int(2) NOT NULL,
`doors` int(1) NOT NULL,
`tax` varchar(5) NOT NULL,
`warranty` int(1) NOT NULL,
`hands` int(1) NOT NULL,
`security` longtext NOT NULL,
`comfort` longtext NOT NULL,
`aesthetic` longtext NOT NULL,
`adreference` varchar(10) NOT NULL,
`ad_price` bigint(20) NOT NULL,
`ad_priceneg` int(1) NOT NULL,
`when_inserted` varchar(20) NOT NULL,
`when_modified` varchar(20) NOT NULL,
`ad_status` int(1) NOT NULL DEFAULT '1' COMMENT '0: not active, 1: active, 2: deleted',
`not_listed` longtext NOT NULL,
PRIMARY KEY (`id_ad`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=6 ;
CREATE TABLE IF NOT EXISTS `ad_vehpro` (
`id_ad` int(10) unsigned NOT NULL AUTO_INCREMENT,
`main_ad` int(5) NOT NULL COMMENT 'this will refer to main table ads (id_ads)',
`id_profiles` varchar(20) NOT NULL,
`city_id` int(5) NOT NULL,
`district_id` int(5) NOT NULL COMMENT 'district id from districts table',
`category_id` int(2) NOT NULL,
`vehpro_type` int(1) NOT NULL,
`make_id` int(5) NOT NULL,
`model_id` int(5) NOT NULL,
`model_year` int(4) NOT NULL,
`engine` int(2) NOT NULL,
`fuel` int(1) NOT NULL,
`mileage` bigint(7) NOT NULL,
`transmission` int(1) NOT NULL,
`wheed_drive` int(1) NOT NULL,
`in_color` varchar(7) NOT NULL,
`ex_color` varchar(7) NOT NULL,
`seats` int(2) NOT NULL,
`doors` int(1) NOT NULL,
`tax` varchar(5) NOT NULL,
`warranty` int(1) NOT NULL,
`hands` int(1) NOT NULL,
`security` longtext NOT NULL,
`comfort` longtext NOT NULL,
`aesthetic` longtext NOT NULL,
`adreference` varchar(10) NOT NULL,
`ad_price` bigint(20) NOT NULL,
`ad_priceneg` int(1) NOT NULL,
`when_inserted` varchar(20) NOT NULL,
`when_modified` varchar(20) NOT NULL,
`ad_status` int(1) NOT NULL DEFAULT '1' COMMENT '0: not active, 1: active, 2: deleted',
`not_listed` longtext NOT NULL,
PRIMARY KEY (`id_ad`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=2 ;
EDITED
I tried using LEFT JOIN but, it skips some fields:
$sqlAds = "SELECT * FROM `ads`"
. " LEFT JOIN ad_car ON ads.id_ads = ad_car.main_ad"
. " LEFT JOIN ad_vehpro ON ads.id_ads = ad_vehpro.main_ad"
. " WHERE ads_cat = :ads_cat AND ads.ad_status = :adStatus ORDER BY date_renewed DESC";
Thanks in advance

Answer 1

List the columns you explicitly want. Provide NULLvalues for the rest:
SELECT a.*, c.col1, c.col2
FROM `ads` a JOIN
ad_car c
ON a.id_ads = c.main_ad
WHERE ads_cat = :ads_cat AND
a.ad_status = :adStatus
UNION
SELECT a.*, v.col1, NULL as col2
FROM ads a JOIN
ad_vehpro v
ON a.id_ads = v.main_ad
WHERE ads_cat = :ads_cat AND
a.ad_status = :adStatus
ORDER BY date_renewed DESC
LIMIT 4;
Note: If you know there are no duplicates between the two subqueries, use UNION ALL rather than UNION. UNION incurs the overhead of removing duplicates.