Exams › GATE › Technical

Consider two relations describing teams and players in a sports league: • teams(tid, tname): tid, tname are team-id and team-name, respectively • players(pid, pname, tid): pid, pname, and tid denote player-id, player-name and the team-id of the player, respectively Which ONE of the following tuple relational calculus queries returns the name of the players who play for the team having tname as 'MI'?

1. { p.pname | p ∈ players ∧ ∃t (t ∈ teams ∧ p.tid = t.tid ∧ t.tname = 'MI') }
2. { p.pname | p ∈ teams ∧ ∃t (t ∈ players ∧ p.tid = t.tid ∧ t.tname = 'MI') }
3. { p.pname | p ∈ players ∧ ∃t (t ∈ teams ∧ t.tname = 'MI') }
4. { p.pname | p ∈ teams ∧ ∃t (t ∈ players ∧ t.tname = 'MI') }

Correct answer: { p.pname | p ∈ players ∧ ∃t (t ∈ teams ∧ p.tid = t.tid ∧ t.tname = 'MI') }

Solution

This option correctly identifies players from the 'players' relation and checks for the existence of a corresponding team in the 'teams' relation that matches the specified team name 'MI', ensuring that only players from that team are selected.

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