SELECT
	dc.id,
	dc.title,
	dc.media_url,
	dc.backup_media_url,
	group_concat(dgc.gateway_id)
FROM data_content as dc
	LEFT JOIN data_gateway_conference as dgc on dgc.content_id = dc.id
WHERE
		(
		TRIM(LOWER(dc.title)) LIKE '%a%'
		OR TRIM(LOWER(dc.media_url)) LIKE '%a%'
		OR TRIM(LOWER(dc.backup_media_url)) LIKE '%a%'
		)
group by dc.id
order by dc.title