Waterfall

SELECT * FROM gallery2 WHERE topic_id="516956" UNION SELECT * FROM gallery2 WHERE topic_id="158392" UNION SELECT * FROM gallery2 WHERE topic_id="784531" UNION SELECT * FROM gallery2 WHERE topic_id="1215469" UNION SELECT * FROM gallery2 WHERE topic_id="648522" UNION SELECT * FROM gallery2 WHERE topic_id="220742" UNION SELECT * FROM gallery2 WHERE topic_id="807239" UNION SELECT * FROM gallery2 WHERE topic_id="1303105" UNION SELECT * FROM gallery2 WHERE topic_id="1159295" UNION SELECT * FROM gallery2 WHERE topic_id="1524690" UNION SELECT * FROM gallery2 WHERE topic_id="1660698" UNION SELECT * FROM gallery2 WHERE topic_id="578487" UNION SELECT * FROM gallery2 WHERE topic_id="116546" UNION SELECT * FROM gallery2 WHERE topic_id="539715" UNION SELECT * FROM gallery2 WHERE topic_id="87979" UNION SELECT * FROM gallery2 WHERE topic_id="1033977"