INSERT INTO video_category(video_id, category_id) VALUES(:video_id, :cat), (:video_id, :cat2)
так: 1,3,4,2 -> cat1,cat3,cat4,cat2
SELECT a.id as id, c.name as category, a.category
FROM artpost_table as a
LEFT JOIN category as c on (a.category = c.id OR CONCAT(', ', a.category, ',') LIKE CONCAT('%, ', c.id, ',%'))
WHERE a.category = '7, 5, 4, 8'
select a.id as id, a.added_date, a.updated_date, a.codename, a.title, a.tech_title, <b><i>c.category_name</i></b>, a.category, f.name as family, d.name as developer, a.os, a.domain, a.FULL_URL, a.publicly_called, a.has_image, a.Available_for_PPC, a.PPC_Risk, a.Is_in_blogs, a.Publish_in_Blog, a.Publish_in_Feed, a.IS_IN_SOFT, a.Has_Tech_Info, u.nick as assigned_to, s.name as status, a.domain_popularity, a.adwords_activity, a.lp, a.seo, a.partners, a.Software_Scan, a.Software_Fix, a.tickets, a.Youtube_URL, a.SEVERITY, a.Image_URL
from artpost_table as a
left join developer as d on a.developer = d.id
left join family as f on a.family = f.id
left join users as u on a.assigned_to = u.id
left join status as s on a.status = s.id
<b><i>left join category as c on a.category = c.id</i></b>
sum(case when (BotItems.itemid = Items.itemid and IFNULL(Items.type, 0) = 1) then 1 else 0 end) as "typecount"
К примеру, как заменить + на _,