我目前正在同一张桌子上试着两次加入。旅行:leaving_loc_code位置:locationselect leavingloc.location,arrivalloc.location from trip
join locations as leavingloc on trip.departureloccode = locations.locationco
SELECT `text`,FROM `oc_product_attribute` AS paLEFT JOIN `oc_product_to_category` AS opc ON pa.`product_id`=od.`product_id`
oc_product_to_category.product_id引起的问题。我把它去掉了,它就起