32 (Q1) Find names of sailors who ' ve reserved boat #103 Reserves(sid, bid, day) Sailors(sid, sname, rating, age) Solution 1: π sname (σ bid = 103 (Reserves ∞ Sailors)) Solution 2 (more efficient) π sname ((σ bid = 103 Reserves) ∞ Sailors) Solution 3 (using rename operator) P(Temp1, σ bid = 103 Reserves) P(Temp2, Temp1 ∞ Sailors) π sname (Temp2)
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