ITPEC FE Subject A April 2026 Question 20
In database normalization, which of the following is the most appropriate description of a table in the third normal form? Here, 2NF stands for the second normal form and 3NF stands for the third normal form.
Explanation
No transitive dependency — a table is in 3NF when it is in 2NF and no non-key attribute depends on the key through another non-key attribute.
Each normal form removes one kind of dependency:
- •1NF: no repeating groups, every value atomic
- •2NF: 1NF plus no partial dependency on part of a composite key
- •3NF: 2NF plus no transitive dependency
Answer (d)
Why not others:
- •(a) — every table has at least one candidate key, so a table without one cannot exist, let alone be 3NF
- •(b) — no partial dependency is what 2NF adds, already given by "in the 2NF"
- •(c) — no repeating group is what 1NF requires
Key rule: 1NF removes repeating groups, 2NF partial dependencies and 3NF transitive dependencies; an option naming an earlier step describes a lower form.
Databases · AI-written, may contain errors
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