SELECT t.*
FROM твоятаблица t
INNER JOIN (
	SELECT id
		,(
			CASE coalesce(field, '') WHEN '' THEN 0 ELSE 1 END + 
			CASE coalesce(field2, '') WHEN '' THEN 0 ELSE 1	END + 
			CASE coalesce(field3, '') WHEN '' THEN 0 ELSE 1 END + 
			CASE coalesce(field4, '') WHEN '' THEN 0 ELSE 1 END + 
			CASE coalesce(field5, '') WHEN '' THEN 0 ELSE 1 END + 
			 CASE coalesce(field6, '') WHEN '' THEN 0 ELSE 1 END
			) AS cnt
	FROM твоятаблица
	) AS a ON a.id = t.id AND a.cnt >= 2