The GATE Grind

GATE 2022 CS – Question 14

Databases · Integrity Constraints and Normal Forms · 1 mark · Multiple choice

In a relational data model, which one of the following statements is TRUE?

  1. A relation with only two attributes is always in BCNF.
  2. If all attributes of a relation are prime attributes, then the relation is in BCNF.
  3. Every relation has at least one non-prime attribute.
  4. BCNF decompositions preserve functional dependencies.

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Show answer and explanation

Correct answer: (A) A relation with only two attributes is always in BCNF.

Explanation

With two attributes, every nontrivial FD has a superkey as its determinant, so the relation is in BCNF. All-prime attributes only guarantee 3NF. A relation can have no non-prime attribute, and BCNF decomposition may lose FDs.