누적 집계 , 10g model
http://www.gurubee.net/lecture/2203
http://blog.naver.com/PostView.nhn?blogId=hjc426&logNo=130037009010&widgetTypeCall=true
oracle lag 앞수, lead 뒷수
http://nown2210.tistory.com/17
http://kodb.or.kr/info/info_06_view.php?dbnum=187315
오라클 피봇, 언피봇, pivot, unpivot
http://www.dbguide.net/db.db?cmd=view&boardUid=13948&boardConfigUid=9&categoryUid=216&boardIdx=97&boardStep=1