%0 Journal Article
%T 广义投影和外连接
%A 严哲南
%A 楼荣生
%J 计算机科学
%D 1999
%I 
%X In this paper we introduce mainly the relation between general projection and outerjoin and the relation between general projection and semijoin. We also put forward pseudodistributive law of general projection. Then we provide a more mature theory about general projection.
%K 数据仓库
%K 聚合查询
%K 广义投影
%K 外连接
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=5B3AB970F71A803DEACDC0559115BFCF0A068CD97DD29835&cid=8240383F08CE46C8B05036380D75B607&jid=64A12D73428C8B8DBFB978D04DFEB3C1&aid=8BEE9808B6341A1A31311B261F83ABF6&yid=B914830F5B1D1078&vid=96C778EE049EE47D&iid=B31275AF3241DB2D&sid=0D0D661F0B316AD5&eid=656F8C8401D91023&journal_id=1002-137X&journal_name=计算机科学&referenced_num=0&reference_num=0