Let R = (A, B) and S = (A, C), and let r(R) and s(S) be relations.
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Let R = (A, B) and S = (A, C), and let r(R) and s(S) be relations. Using the special constant null, write tuple-relational-calculus expressions equivalent to each of the following:
a. r 1 s
b. r 1 s
c. r 1 s
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a t r R s S rA sA tA rA tB rB tC sC s S r RrA sA tA sA tC sC tB n...View the full answer
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