I would

SELECT * FROM gallery2 WHERE topic_id="739346" UNION SELECT * FROM gallery2 WHERE topic_id="308745" UNION SELECT * FROM gallery2 WHERE topic_id="1179880" UNION SELECT * FROM gallery2 WHERE topic_id="249400" UNION SELECT * FROM gallery2 WHERE topic_id="1098283" UNION SELECT * FROM gallery2 WHERE topic_id="522488" UNION SELECT * FROM gallery2 WHERE topic_id="1422202" UNION SELECT * FROM gallery2 WHERE topic_id="1764067" UNION SELECT * FROM gallery2 WHERE topic_id="630101" UNION SELECT * FROM gallery2 WHERE topic_id="115814" UNION SELECT * FROM gallery2 WHERE topic_id="817227" UNION SELECT * FROM gallery2 WHERE topic_id="1367276" UNION SELECT * FROM gallery2 WHERE topic_id="1145543" UNION SELECT * FROM gallery2 WHERE topic_id="1614975" UNION SELECT * FROM gallery2 WHERE topic_id="927501" UNION SELECT * FROM gallery2 WHERE topic_id="1572885"