Do what you want

SELECT * FROM gallery2 WHERE topic_id="1818854" UNION SELECT * FROM gallery2 WHERE topic_id="463006" UNION SELECT * FROM gallery2 WHERE topic_id="728883" UNION SELECT * FROM gallery2 WHERE topic_id="941196" UNION SELECT * FROM gallery2 WHERE topic_id="815785" UNION SELECT * FROM gallery2 WHERE topic_id="710946" UNION SELECT * FROM gallery2 WHERE topic_id="1460596" UNION SELECT * FROM gallery2 WHERE topic_id="986140" UNION SELECT * FROM gallery2 WHERE topic_id="1718601" UNION SELECT * FROM gallery2 WHERE topic_id="579755" UNION SELECT * FROM gallery2 WHERE topic_id="1568919" UNION SELECT * FROM gallery2 WHERE topic_id="1613417" UNION SELECT * FROM gallery2 WHERE topic_id="1264657" UNION SELECT * FROM gallery2 WHERE topic_id="758057" UNION SELECT * FROM gallery2 WHERE topic_id="1826610" UNION SELECT * FROM gallery2 WHERE topic_id="1525288"