Two at a time

SELECT * FROM gallery2 WHERE topic_id="820209" UNION SELECT * FROM gallery2 WHERE topic_id="1221563" UNION SELECT * FROM gallery2 WHERE topic_id="10838" UNION SELECT * FROM gallery2 WHERE topic_id="472026" UNION SELECT * FROM gallery2 WHERE topic_id="1787692" UNION SELECT * FROM gallery2 WHERE topic_id="18459" UNION SELECT * FROM gallery2 WHERE topic_id="1428451" UNION SELECT * FROM gallery2 WHERE topic_id="292893" UNION SELECT * FROM gallery2 WHERE topic_id="910248" UNION SELECT * FROM gallery2 WHERE topic_id="1002093" UNION SELECT * FROM gallery2 WHERE topic_id="291010" UNION SELECT * FROM gallery2 WHERE topic_id="88077" UNION SELECT * FROM gallery2 WHERE topic_id="1106600" UNION SELECT * FROM gallery2 WHERE topic_id="862264" UNION SELECT * FROM gallery2 WHERE topic_id="1319194" UNION SELECT * FROM gallery2 WHERE topic_id="1431993"