You can hold them if you want

SELECT * FROM gallery2 WHERE topic_id="945168" UNION SELECT * FROM gallery2 WHERE topic_id="1356754" UNION SELECT * FROM gallery2 WHERE topic_id="1771363" UNION SELECT * FROM gallery2 WHERE topic_id="300264" UNION SELECT * FROM gallery2 WHERE topic_id="388119" UNION SELECT * FROM gallery2 WHERE topic_id="1330476" UNION SELECT * FROM gallery2 WHERE topic_id="659204" UNION SELECT * FROM gallery2 WHERE topic_id="631950" UNION SELECT * FROM gallery2 WHERE topic_id="452082" UNION SELECT * FROM gallery2 WHERE topic_id="872242" UNION SELECT * FROM gallery2 WHERE topic_id="1731684" UNION SELECT * FROM gallery2 WHERE topic_id="1343504" UNION SELECT * FROM gallery2 WHERE topic_id="937503" UNION SELECT * FROM gallery2 WHERE topic_id="1495844" UNION SELECT * FROM gallery2 WHERE topic_id="1162110" UNION SELECT * FROM gallery2 WHERE topic_id="1274269"