18 Questions
What is the primary goal of relation decomposition?
To ensure each individual relation is in BCNF or 3NF
What is the attribute preservation condition of a decomposition?
Each attribute in R appears in at least one relation schema Ri
Why is it not sufficient to consider individual relations in a decomposition to guarantee a good database design?
Because the decomposition as a whole must be considered
What is the purpose of specifying the set F of FDs that should hold on the attributes of R?
To make the FDs available to the design algorithms
What is the dependency preservation condition of a decomposition?
FD X → Y can be inferred from the dependencies that appear in some Ri
What is the result of decomposing the universal relation R into a set of relation schemas D?
A set of relations that together form the relational database
What is the relation EMPLOYEE_3 based on?
Only tuples where Dnum is not NULL
What is a challenge in normalization algorithms?
They are not always deterministic
What is a multivalued dependency (MVD) in a relation schema?
A constraint on multiple tuples in a relation
What is required to specify all the relevant dependencies among database attributes?
All functional dependencies
What is the goal of normalization algorithms?
To achieve BCNF and preserve dependencies
What is a trivial multivalued dependency (MVD)?
An MVD where Y is a subset of X or X υ Y is equal to R
What is a functional dependency between two sets of attributes X and Y?
The value of X determines a unique value for Y
What is the dependency preservation property in relational database design?
A decomposition that preserves all functional dependencies
What is the purpose of finding the minimal cover of a set of functional dependencies?
To eliminate redundant dependencies
What is the nonadditive (or lossless) join property in relational database design?
A decomposition that preserves data during join
What is the purpose of the inference rules for functional dependencies?
To derive new functional dependencies
What do functional dependencies represent in a relational database?
Real-world constraints on the attributes
This quiz covers database relation decomposition, normal forms, and functional dependencies. It discusses the importance of a good design and how individual relations may not guarantee a good design.
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