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163206 Homework

1. Consider the following model (primary keys are underlined) for storing historical data about who has competed in all the Olympic events, and how their teams finished.

Results (year, event, finish position, team)

Participants (team, year, participant, country, event)

The first relation records which team earned each “place” (i.e., 1st, 2nd, etc.) for each event in a given year. There are no ties. The second relation encodes team membership. Assume that even events with individual competitors are stored in the database as (single-person) teams.

Express the following queries in relational algebra.

(a) What team won 1st place for Handball in 1942?

(b) List the members of that winning Handball team.

(c) Give a history of Canadian performance in the Olympics: for each year, list each Canadian team, the event, and its finish position.

Kĩ năng: Bất kì công việc gì, Viết lại bài báo

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