Опитайте това:
SELECT *
FROM tablename
WHERE keywordId IN (1, 12)
GROUP BY articleId
HAVING COUNT(*) = 2;
Проверете ДЕМО НА FIDDLE SQL
Опитайте това:
SELECT *
FROM tablename
WHERE keywordId IN (1, 12)
GROUP BY articleId
HAVING COUNT(*) = 2;
Проверете ДЕМО НА FIDDLE SQL