IPA FE Subject A 2023 Question 6
A question IPA Japan published in 令和５年度 基本情報技術者試験 科目A 公開問題 問6, translated into English. ITPEC is based on the same exams.
Same question on ITPEC: Oct 2025 Q19
When the functional dependencies shown below are satisfied, which of the following is the transitive functional dependency that holds? Here, “A→B” indicates that B is functionally dependent on A, and “A→{B, C}” indicates that “A→B” and “A→C” both hold.
[Functional dependencies]
{OrderCode, ProductCode} → {CustomerOrderQuantity, OrderAmount}
OrderCode → {OrderDate, CustomerCode, OrderManagerCode}
ProductCode → {ProductName, SupplierCode, ProductSalePrice}
SupplierCode → {SupplierName, SupplierAddress, SupplierManagerCode}
CustomerCode → {CustomerName, CustomerAddress}
Explanation
OrderCode → CustomerCode → CustomerAddress — both steps are given dependencies, and the middle attribute does not determine OrderCode.
A transitive functional dependency X → Y → Z needs X → Y and Y → Z to hold while Y does not determine X; Z then depends on X only through Y.
- •OrderCode → CustomerCode: given in the second line
- •CustomerCode → CustomerAddress: given in the fifth line
- •CustomerCode does not determine OrderCode, since one customer places many orders
Answer (a)
Why not others:
- •(b) — OrderCode does not determine ProductCode: one order holds several products, and CustomerOrderQuantity depends on the pair {OrderCode, ProductCode}
- •(c) — SupplierCode does not determine ProductSalePrice: one supplier supplies many products at different prices, and the price depends on ProductCode directly
- •(d) — SupplierManagerCode → SupplierAddress is not given; SupplierAddress depends on SupplierCode directly, and one manager may handle several suppliers
Key rule: Check every arrow of a proposed chain against the given dependencies, since one missing arrow breaks it; transitive dependencies are what third normal form removes.
Databases · AI-written, may contain errors
This question comes from the past questions IPA Japan publishes, translated into English by ITPEC Practice. ITPEC Practice is an independent study tool and is not affiliated with IPA or ITPEC. See the original paper (PDF) or Report an issue.