Simple

SELECT * FROM gallery2 WHERE topic_id="208117" UNION SELECT * FROM gallery2 WHERE topic_id="1749576" UNION SELECT * FROM gallery2 WHERE topic_id="980460" UNION SELECT * FROM gallery2 WHERE topic_id="1517282" UNION SELECT * FROM gallery2 WHERE topic_id="1792659" UNION SELECT * FROM gallery2 WHERE topic_id="1452548" UNION SELECT * FROM gallery2 WHERE topic_id="1058662" UNION SELECT * FROM gallery2 WHERE topic_id="279076" UNION SELECT * FROM gallery2 WHERE topic_id="245433" UNION SELECT * FROM gallery2 WHERE topic_id="761666" UNION SELECT * FROM gallery2 WHERE topic_id="1157103" UNION SELECT * FROM gallery2 WHERE topic_id="837986" UNION SELECT * FROM gallery2 WHERE topic_id="1568838" UNION SELECT * FROM gallery2 WHERE topic_id="1274163" UNION SELECT * FROM gallery2 WHERE topic_id="433416" UNION SELECT * FROM gallery2 WHERE topic_id="591643"