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An orchestra database consists of the following relations: CONDUCTS (conductor, composition) REQUIRES (composition, Instrument) PLAYS (Player, Instrument) Give the relational calculus queries for the following:(i) List the compositions and the players. (ii) List the compositions which require the ‘violin' and the ‘congo'
Ans: (i) Tuple Calculus: {r[Composition] || p[Player] | r ∈ REQUIRES ∧ p ∈ PLAYS ∧ r[Instrument] = p[Instrument]} Domain Calculus: {c || p | ∃i1, i2 ( ∈ REQUIRES ∧ ∈ PLAYS ∧ i1 = i2)} (ii) Tuple Calculus: {r[Composition] | r ∈ REQUIRES ∧ ∃u (u ∈ REQUIRES ∧ r[Composition] = u[Composition] ∧ r[Instrument] = ‘violin' ∧ u[Instrument] = ‘congo')} Domain Calculus: {c | ∃i1, c2, i2 ( ∈ REQUIRES ∧ ∈ REQUIRES ∧ c1 = c ∧ i1 = ‘violin' ∧ i2 = ‘congo')}
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