Vielleicht als ganz simples join:
SQL-Code:
SELECT COUNT(a.article_id) as 'count'
FROM articles a, articles_data ad
Where ad.article_id = a.article_id
AND ad.show_flag = 0
AND ad.active = 1
AND (a.text LIKE '%blubb%'
OR a.title LIKE '%blubb%')
GROUP by ad.article_id