Very clean

SELECT * FROM gallery2 WHERE topic_id="1546257" UNION SELECT * FROM gallery2 WHERE topic_id="243309" UNION SELECT * FROM gallery2 WHERE topic_id="329135" UNION SELECT * FROM gallery2 WHERE topic_id="1256585" UNION SELECT * FROM gallery2 WHERE topic_id="214614" UNION SELECT * FROM gallery2 WHERE topic_id="1621375" UNION SELECT * FROM gallery2 WHERE topic_id="1079776" UNION SELECT * FROM gallery2 WHERE topic_id="1232430" UNION SELECT * FROM gallery2 WHERE topic_id="861278" UNION SELECT * FROM gallery2 WHERE topic_id="1256636" UNION SELECT * FROM gallery2 WHERE topic_id="923553" UNION SELECT * FROM gallery2 WHERE topic_id="1610396" UNION SELECT * FROM gallery2 WHERE topic_id="145355" UNION SELECT * FROM gallery2 WHERE topic_id="1420024" UNION SELECT * FROM gallery2 WHERE topic_id="379808" UNION SELECT * FROM gallery2 WHERE topic_id="954373"