I think you know what to do

SELECT * FROM gallery2 WHERE topic_id="986807" UNION SELECT * FROM gallery2 WHERE topic_id="595496" UNION SELECT * FROM gallery2 WHERE topic_id="1177506" UNION SELECT * FROM gallery2 WHERE topic_id="1458254" UNION SELECT * FROM gallery2 WHERE topic_id="954742" UNION SELECT * FROM gallery2 WHERE topic_id="1624194" UNION SELECT * FROM gallery2 WHERE topic_id="642562" UNION SELECT * FROM gallery2 WHERE topic_id="80561" UNION SELECT * FROM gallery2 WHERE topic_id="3267" UNION SELECT * FROM gallery2 WHERE topic_id="922189" UNION SELECT * FROM gallery2 WHERE topic_id="342127" UNION SELECT * FROM gallery2 WHERE topic_id="1717449" UNION SELECT * FROM gallery2 WHERE topic_id="385280" UNION SELECT * FROM gallery2 WHERE topic_id="1336653" UNION SELECT * FROM gallery2 WHERE topic_id="1053624" UNION SELECT * FROM gallery2 WHERE topic_id="326142"