ads table img90.imageshack.us/img90/6295/adsvo.png phones table img194.imageshack.us/img194/3713/phones.png cars table img35.imageshack.us/img35/1035/carsm.png i have 3 tables ads,cars and phones. i want to join tables is based on category in ads table. and i tried this query but no luck,any helps? SELECT * FROM `ads` JOIN `ads.category` ON `ads.id` = `ads.category.id` ** i cant add comment any of your post,but i want it to be automatic based on category in ads table. for example :- if in table have phones category,i will automatic join phones table then SELECT * FROM `ads` JOIN `phone` ON `ads.id` = `phone.id` if in table have cars category,i will automatic join cars table SELECT * FROM `ads` JOIN `cars` ON `ads.id` = `cars.id`