11A minimal set of attributes that uniquely identifies each tuple is a:ACandidate keyBComposite attributeCSuper keyDForeign keyView AnswerDiscussWorkspaceReportSaveEasy
12Which operation returns tuples in R but not in S?ADivisionBUnionCIntersectionDSet difference (R − S)View AnswerDiscussWorkspaceReportSaveEasy
13Which relational algebra operation removes duplicate columns and keeps only specified attributes?ADivision (÷)BSelection (σ)CProjection (π)DJoin (⋈)View AnswerDiscussWorkspaceReportSaveMedium
14A primary key made of more than one attribute is a:APartial keyBComposite keyCForeign keyDSurrogate keyView AnswerDiscussWorkspaceReportSaveEasy
15Which relational algebra operation combines tuples from two relations that match a condition?ADifference (−)BUnion (∪)CJoin (⋈)DProjection (π)View AnswerDiscussWorkspaceReportSaveEasy