Take

SELECT * FROM gallery2 WHERE topic_id="501635" UNION SELECT * FROM gallery2 WHERE topic_id="1248850" UNION SELECT * FROM gallery2 WHERE topic_id="912557" UNION SELECT * FROM gallery2 WHERE topic_id="933685" UNION SELECT * FROM gallery2 WHERE topic_id="1762216" UNION SELECT * FROM gallery2 WHERE topic_id="377722" UNION SELECT * FROM gallery2 WHERE topic_id="847907" UNION SELECT * FROM gallery2 WHERE topic_id="1442693" UNION SELECT * FROM gallery2 WHERE topic_id="1106963" UNION SELECT * FROM gallery2 WHERE topic_id="836307" UNION SELECT * FROM gallery2 WHERE topic_id="1366668" UNION SELECT * FROM gallery2 WHERE topic_id="651873" UNION SELECT * FROM gallery2 WHERE topic_id="165007" UNION SELECT * FROM gallery2 WHERE topic_id="1746276" UNION SELECT * FROM gallery2 WHERE topic_id="1001298" UNION SELECT * FROM gallery2 WHERE topic_id="1652735"