Database Question: TRUE or FALSE 1. A schema where all the relations are in BCNF

Question

Database Question: TRUE or FALSE

1. A schema where all the relations are in BCNF may have update anomalies involving key attributes.

2. Failure to preserve dependencies can result in lossy joins.

3. A lossless decomposition is considered preferable to a lossy decomposition.

4. 3NF can give better performance than BCNF due to fewer joins.

5. Primary keys represent dependencies that are automatically enforced by a relational DBMS.

6. If the intersection of attributes (not the intersection of the data) in two relations is empty, then the join of the two relations is lossless.

7. Spurious tuples result from joining poorly decomposed relations.

8. A schema where all relations are in 3NF may have update anomalies involving key attributes.

Explanation / Answer

1. A schema where all the relations are in BCNF may have update anomalies involving key attributes-True

2. Failure to preserve dependencies can result in lossy joins-False

3. A lossless decomposition is considered preferable to a lossy decomposition-False

4. 3NF can give better performance than BCNF due to fewer joins-True

5. Primary keys represent dependencies that are automatically enforced by a relational DBMS-True

6. If the intersection of attributes (not the intersection of the data) in two relations is empty, then the join of the two relations is lossless-False

7. Spurious tuples result from joining poorly decomposed relations-True

8. A schema where all relations are in 3NF may have update anomalies involving key attributes-True

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