Project ForgeA database of research articles in a journal uses the schema (Volume, Number, StartPage, EndPage, Title, Year, Price), with primary key (Volume, Number, StartPage, EndPage) and functional dependencies: (Volume, Number, StartPage, EndPage) → Title (Volume, Number) → Year (Volume, Number, StartPage, EndPage) → Price
The database is redesigned into two schemas: (Volume, Number, StartPage, EndPage, Title, Price) (Volume, Number, Year)
Which is the weakest normal form that the NEW database satisfies, but the OLD one does not?
- A1NF
- 2NF
- C3NF
- DBCNF
Explanation
In the OLD schema, (Volume, Number) is a proper SUBSET of the primary key (Volume,Number,StartPage,EndPage), yet it determines the non-prime attribute Year — a classic partial dependency, which violates 2NF (the old schema is only in 1NF). In the NEW schema, each relation's non-prime attributes depend on the WHOLE of their own key (the first relation's key is its entire attribute set except Title/Price which fully depend on it; the second relation's key is (Volume,Number), which now trivially determines Year without any partial-dependency issue) — satisfying 2NF, 3NF, and even BCNF. The weakest normal form where the two databases first differ is 2NF.
Source: GATE CS 2016 (Session 1 / Set A) (2016)
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