ITPEC FE Morning April 2018 Question 27

Functional Dependency — identify which X → Y holds in a table.

Check each option for counterexamples (same X, different Y):

• •(a) Delivery_date → Component_ID — 2016-08-30 maps to both 2346 and 1342 ✗
• •(b) Delivery_destination → Component_ID — Chicago office → 1342, Boston factory → 2346, New York office → 1342 — each destination maps to exactly one Component_ID ✓
• •(c) Department_ID → Component_ID — 500 maps to both 2346 and 1342 ✗
• •(d) Department_name → Delivery_destination — Research and development department maps to both Boston factory and New York office ✗

Key rule: X → Y means every X value maps to exactly one Y value. Find a single counterexample to disprove.

AI-generated — may contain errors