Using the Entity Relationship Diagram you have drawn on your piece of paper for the Hamilton Island 'BoatRaceResults' Table, answer the following question.

Which attribute is fully Dependent on the primary key of the BoatRaceResults table?

Question

Using the Entity Relationship Diagram you have drawn  on your piece of paper for the Hamilton Island 'BoatRaceResults' Table, answer the following question.

Which attribute is fully Dependent on the primary key of the BoatRaceResults table?

BlackTom AI · Accepted Answer

Reviewing the BoatRaceResults table and its functional dependencies helps determine which attributes rely on the primary key.
Option 1: None exist
- This would mean no attribute is entirely dependent on the primary key, which contradicts the given FD where certain attributes clearly depend on the key. The dependencies show that at least one attribute is tied to the key, so this option is incorrect.
Option 2: Place
- The functional dependencies state that RaceID and BoatName together determine Handicap, Place, and Skipper. This means Place depends on the combination of RaceID and BoatName, i.e., on the full (composite) primary key (RaceID, BoatName). Since it does not depend on just RaceID or just BoatName alone, it is a full (complete) dependency with respect to the composite key. This aligns with the concept of a fully dependent attribute in a candidate key decomposition.
Option 3: RaceDate
- RaceDate is determined by RaceID alone (RaceID -> RaceDate). Since the primary key is the combination (RaceID, BoatName), RaceDate depends on only a part of the composite key (RaceID). This is a partial dependency, not a full one, so it is not fully dependent on the primary key.
Option 4: ClubSuburb
- ClubSuburb depends on Club, and Club in turn depends on BoatName (BoatName -> BoatSaleNum, BoatClub; BoatClub -> ClubSuburb). This is a transitive dependency chain from the primary key through BoatName and BoatClub to ClubSuburb, not a direct full dependency on the primary key. It therefore does not satisfy full dependency criteria.
Option 5: BoatSaleNum
- BoatSaleNum depends on BoatName (BoatName -> BoatSaleNum). Since BoatName is only part of the composite key, this is another partial/derived dependency rather than a full dependency on the entire key. It does not meet the criterion for fully dependent on the primary key.
In summary, among the listed attributes, Place is the one that is tied to the full (RaceID, BoatName) key rather than to just a part of the key or through transitive/partial paths, according to the functional dependencies provided.

Using the Entity Relationship Diagram you have drawn on your piece of paper for the Hamilton Island 'BoatRaceResults' Table, answer the following question. Which attribute is fully Dependent on the primary key of the BoatRaceResults table?单项选择题

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