Database 1 Data Manipulation

Beer question n (tupel calculus)

This answer is wrong: Suppose there are 2 beers a, b, 1 bar k, 2 drinkers x, y; everyone serves/visits/likes everything Then the correct answer should result in {a, b}. The tupel calculus expression: does not contain a, because every visitor of k also likes b. The answer should have been:

Common tupel calculus mistakes

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