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计算机科学 1999
广义投影和外连接Keywords: 数据仓库聚合查询广义投影外连接 Abstract: inthispaperweintroducemainlytherelationbetweengeneralprojectionandouterjoinandtherelationbetweengeneralprojectionandsemijoin.wealsoputforwardpseudodistributivelawofgeneralprojection.thenweprovideamorematuretheoryabout
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