Normalization— Concepts, Formulas & Shortcuts
- 1NF: every column holds atomic values — no repeating groups or comma-separated lists.
- 2NF: 1NF plus no partial dependency — no non-key column depends on only part of a composite primary key.
- 3NF: 2NF plus no transitive dependency — non-key columns must not depend on other non-key columns.
- BCNF: a stricter 3NF where every determinant is a candidate key.
- Normalisation removes redundancy and anomalies; denormalisation reintroduces redundancy deliberately to speed up reads.
- Insert, update and delete anomalies are the practical symptoms of a poorly normalised design.
Normalization Practice Questions with Answers
Attempt each question first, then open the explanation. All 6 questions below are free to read and require no signup.
Q1.A table is in 1NF if:
Easy- AIt has a primary key
- BAll column values are atomic
- CIt has no transitive dependency
- DIt has no partial dependency
Normalization question 1 of 6+Show Answer & Explanation
Answer: B. All column values are atomic
Explanation: First normal form requires atomic (indivisible) values with no repeating groups or multi-valued columns.
Q2.Second normal form eliminates:
Moderate- ATransitive dependency
- BPartial dependency
- CMulti-valued dependency
- DJoin dependency
Normalization question 2 of 6+Show Answer & Explanation
Answer: B. Partial dependency
Explanation: 2NF requires that every non-key attribute depend on the whole composite key, not just part of it.
Q3.Third normal form eliminates:
Moderate- APartial dependency
- BTransitive dependency
- CAtomicity violations
- DForeign key violations
Normalization question 3 of 6+Show Answer & Explanation
Answer: B. Transitive dependency
Explanation: 3NF removes dependencies where a non-key attribute determines another non-key attribute.
Q4.BCNF is a stricter version of:
Moderate- A1NF
- B2NF
- C3NF
- D4NF
Normalization question 4 of 6+Show Answer & Explanation
Answer: C. 3NF
Explanation: Boyce–Codd Normal Form strengthens 3NF by requiring every determinant to be a candidate key.
Q5.Which of these is a benefit of normalisation?
Easy- AFaster reads on every query
- BReduced data redundancy and fewer update anomalies
- CFewer tables
- DAutomatic indexing
Normalization question 5 of 6+Show Answer & Explanation
Answer: B. Reduced data redundancy and fewer update anomalies
Explanation: Normalisation targets redundancy and anomalies. It often increases the number of tables and the number of joins needed.
Q6.Deliberately introducing redundancy to improve read performance is called:
Easy- ANormalisation
- BDenormalisation
- CIndexing
- DSharding
Normalization question 6 of 6+Show Answer & Explanation
Answer: B. Denormalisation
Explanation: Denormalisation trades storage and write complexity for fewer joins on read-heavy workloads.
Normalization — Frequently Asked Questions
What is the difference between 2NF and 3NF?+
2NF removes partial dependencies on a composite key — a non-key column must depend on the whole key. 3NF removes transitive dependencies — a non-key column must not depend on another non-key column.
Is full normalisation always desirable?+
No. Highly normalised schemas need more joins, which can hurt read-heavy analytics workloads. Production systems often denormalise deliberately, trading storage and write complexity for read speed.
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