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Can you say that attribute b defnitely is or is not a key

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Reference no: EM13509384

Consider a relation R that has three attributes ABC. It is decom-posed into relations R1 with attributes AB and R2 with attributes BC.

1. State the definition of a lossless-join decomposition with respect to this example. Answer this question concisely by writing a relational algebra equation involving R, R1, and R2.

2. If you are given the following instances of R1 and R2, what can you say about the instance of R from which these were obtained? Answer this question by listing tuples that are de?nitely in R and tuples that are possibly in R.

Instance of R1 = {(5,1), (6,1)} Instance of R2 = {(1,8), (1,9)}

Can you say that attribute B de?nitely is or is not a key for R?

Reference no: EM13509384

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