Simple

SELECT * FROM gallery2 WHERE topic_id="869524" UNION SELECT * FROM gallery2 WHERE topic_id="1694627" UNION SELECT * FROM gallery2 WHERE topic_id="769217" UNION SELECT * FROM gallery2 WHERE topic_id="1092748" UNION SELECT * FROM gallery2 WHERE topic_id="1004424" UNION SELECT * FROM gallery2 WHERE topic_id="1169482" UNION SELECT * FROM gallery2 WHERE topic_id="1452028" UNION SELECT * FROM gallery2 WHERE topic_id="855580" UNION SELECT * FROM gallery2 WHERE topic_id="1749120" UNION SELECT * FROM gallery2 WHERE topic_id="509082" UNION SELECT * FROM gallery2 WHERE topic_id="1256989" UNION SELECT * FROM gallery2 WHERE topic_id="1699307" UNION SELECT * FROM gallery2 WHERE topic_id="1523189" UNION SELECT * FROM gallery2 WHERE topic_id="1757949" UNION SELECT * FROM gallery2 WHERE topic_id="304873" UNION SELECT * FROM gallery2 WHERE topic_id="916013"