Which of the following statements about dependency preservation is true?Dependency preservation ensures that all relations are in 2nd Normal Form (2NF).It guarantees that no transitive dependencies exist in a relation.Dependency preservation is only relevant for relations with composite keys.It ensures that the decomposition of relations during normalization maintains the same functional dependencies.
Question
Which of the following statements about dependency preservation is true?Dependency preservation ensures that all relations are in 2nd Normal Form (2NF).It guarantees that no transitive dependencies exist in a relation.Dependency preservation is only relevant for relations with composite keys.It ensures that the decomposition of relations during normalization maintains the same functional dependencies.
Solution
The correct statement about dependency preservation is: "It ensures that the decomposition of relations during normalization maintains the same functional dependencies."
Here's why:
-
Dependency preservation does not ensure that all relations are in 2nd Normal Form (2NF). The 2NF is a state of a relation that fulfills a specific condition related to the dependencies of non-prime attributes on the primary key. It doesn't have a direct connection with dependency preservation.
-
It does not guarantee that no transitive dependencies exist in a relation. Transitive dependency is a concept related to 3rd Normal Form (3NF), not directly related to dependency preservation.
-
Dependency preservation is not only relevant for relations with composite keys. It is a property that is desirable in any decomposition of a relation, regardless of whether the keys are composite or not.
-
Dependency preservation ensures that the decomposition of relations during normalization maintains the same functional dependencies. This is true. When a database is normalized and relations are decomposed, it is desirable to preserve the functional dependencies so that the original relation can be reconstructed if necessary.
Similar Questions
What does dependency preservation refer to in the database normalization?Ensuring that all functional dependencies are maintained during the normalization processEliminating all functional dependencies to simplify the database structureMinimizing data redundancy by organizing data into tables and columnsEnsuring that all relations are in Boyce-Codd Normal Form (BCNF)Next
When is a relation considered to be in second normal form (2NF)? (Select the best answer.)Select one:a.When there are no repeating groups in a relationb.When there are no transitive functional dependenciesc.When there are no dependencies on part of the primary keyd.When there are no dependent attributes in transitive relation
Properties of RelationalDecompositions (3) Dependency Preservation Property of aDecomposition: Definition: Given a set of dependencies F on R,the projection of F on Ri, denoted by Ri(F) whereRi is a subset of R, is the set of dependenciesX Y in F+ such that the attributes in X υ Y are allcontained in Ri. Hence, the projection of F on each relationschema Ri in the decomposition D is the set offunctional dependencies in F+, the closure of F,such that all their left- and right-hand-sideattributes are in Ri.
Which one of the following statements about normal forms is FALSE? (PERSISTENT)Options: Pick one correct answer from belowLossless, dependency -preserving decomposition into 3 NF is always possibleBCNF is stricter than 3 NFLoss less, dependency – preserving decomposition into BCNF is always possibleAny relation with two attributes is BCNF
Which statement best describes the purpose of Second Normal Form (2NF)?a.2NF allows redundancy to be eliminated completely from the relationb.2NF allows for the nesting of relations within relations, enhancing data organizationc.2NF ensures that every non-prime attribute is fully functionally dependent on the entire candidate key, thus removing partial functional dependenciesd.2NF ensures that every attribute in the relation is functionally dependent on the primary key
Upgrade your grade with Knowee
Get personalized homework help. Review tough concepts in more detail, or go deeper into your topic by exploring other relevant questions.