Database Normalization Chapter Review
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Questions and Answers

What is the primary focus of the chapter on normalization?

  • To describe data redundancy in database design.
  • To compare different database management systems.
  • To introduce functional dependencies and normalization. (correct)
  • To explain database user interfaces.

Which section discusses the potential problems associated with data redundancy?

  • Section 14.5
  • Section 14.7
  • Section 14.1
  • Section 14.3 (correct)

Functional dependency is important in normalization as it describes what?

  • The performance efficiency of queries.
  • The relationship between attributes. (correct)
  • The security measures for data access.
  • The method of retrieving data from a database.

Which normal form is primarily addressed in Section 14.6?

<p>First Normal Form (1NF) (A)</p> Signup and view all the answers

In which section is the overview of normalization presented?

<p>Section 14.5 (B)</p> Signup and view all the answers

How are the definitions for 2NF and 3NF provided in Section 14.9 different?

<p>They consider all candidate keys. (D)</p> Signup and view all the answers

What common issue does normalization primarily aim to address?

<p>Data redundancy. (C)</p> Signup and view all the answers

Which of the following is NOT a focus of the normalization chapter?

<p>Data visualization techniques. (A)</p> Signup and view all the answers

What characterizes a full functional dependency?

<p>A dependency that has no proper subsets influencing it. (D)</p> Signup and view all the answers

Which of the following is an example of a partial dependency?

<p>staffNo, sName ® branchNo (C)</p> Signup and view all the answers

In the given context, which statement is true about functional dependency?

<p>The relationship must be one-to-one for proper normalization. (C)</p> Signup and view all the answers

What happens when an attribute is removed from a full functional dependency?

<p>The dependency ceases to exist. (D)</p> Signup and view all the answers

Which example illustrates a full functional dependency?

<p>staffNo ® branchNo (B)</p> Signup and view all the answers

What is the key difference between partial and full functional dependencies?

<p>Partial dependencies allow subsets to still maintain the dependency. (D)</p> Signup and view all the answers

How is a functional dependency indicated in this context?

<p>By using an arrow. (B)</p> Signup and view all the answers

What is the primary objective of normalization in database design?

<p>To accurately represent data and relationships (A)</p> Signup and view all the answers

Why is identifying full functional dependencies crucial in normalization?

<p>They reduce redundancy and improve database design. (A)</p> Signup and view all the answers

Which normal form is characterized by the elimination of duplicate attributes in a relation?

<p>First Normal Form (1NF) (B)</p> Signup and view all the answers

What role do functional dependencies play in normalization?

<p>They describe relationships between attributes (D)</p> Signup and view all the answers

What happens if the last staff member of a branch is deleted from the StaffBranch relation?

<p>The branch details are lost from the database. (D)</p> Signup and view all the answers

Which of the following describes Second Normal Form (2NF)?

<p>There are no partial dependencies of any attribute on a primary key. (B)</p> Signup and view all the answers

What is a potential problem associated with redundant data in database relations?

<p>Complications in data integrity (A)</p> Signup and view all the answers

How is the problem of deletion anomalies avoided in a properly designed database?

<p>By storing branch details separately from staff details. (D)</p> Signup and view all the answers

What characteristic is NOT a requirement for a relation to be in Third Normal Form (3NF)?

<p>It must have multiple candidate keys. (B)</p> Signup and view all the answers

What issue arises when modifying the address of a branch in the StaffBranch relation?

<p>All staff tuples for that branch must be updated. (D)</p> Signup and view all the answers

What is a modification anomaly?

<p>The need to update several tuples for one change. (A)</p> Signup and view all the answers

How does normalization benefit the design of a relational database?

<p>By grouping attributes into relations that meet known normal forms (A)</p> Signup and view all the answers

What is the first step in the normalization process?

<p>Identifying functional dependencies (C)</p> Signup and view all the answers

What is a key difference between the StaffBranch relation and the separate Staff and Branch relations?

<p>The StaffBranch relation is more prone to update anomalies. (C)</p> Signup and view all the answers

What occurs if the update of branch address for one staff member is overlooked?

<p>The branch may show different addresses in various tuples. (A)</p> Signup and view all the answers

Why does the StaffBranch relation demonstrate undesirable properties?

<p>It results in loss of information when deleting tuples. (A)</p> Signup and view all the answers

What is a common result of update anomalies in the StaffBranch relation?

<p>Staff tuples may represent outdated information. (C)</p> Signup and view all the answers

What transformation is required to convert the ClientRental relation into 2NF?

<p>Splitting the relation into three new relations (C)</p> Signup and view all the answers

What is a defining characteristic of a relation in Third Normal Form (3NF)?

<p>It contains no transitive dependencies. (D)</p> Signup and view all the answers

Which attributes are part of the Client relation after normalization?

<p>clientNo and cName (D)</p> Signup and view all the answers

What issue does the update anomaly in the PropertyOwner relation highlight?

<p>Challenges in data integrity (C)</p> Signup and view all the answers

Which of the following is NOT a goal of moving to 3NF?

<p>Simplifying query performance (B)</p> Signup and view all the answers

What contributes to the ClientRental relation being not in 2NF?

<p>Partial dependencies on the primary key (C)</p> Signup and view all the answers

In the normalized structure, which relation includes the rent and owner details?

<p>PropertyOwner (C)</p> Signup and view all the answers

Which attribute is part of the Rental relation in the normalized form?

<p>rentFinish (D)</p> Signup and view all the answers

What does the process of removing partially dependent attributes from a relation achieve?

<p>Reduces redundancy by ensuring all attributes depend on the primary key (D)</p> Signup and view all the answers

Which of the following represents a partial dependency identified in the ClientRental relation?

<p>clientNo -&gt; cName (A)</p> Signup and view all the answers

How do you confirm that the ClientRental relation is not in 2NF?

<p>Some attributes depend only on a part of the primary key. (D)</p> Signup and view all the answers

Which functional dependency indicates a transitive dependency in the ClientRental relation?

<p>ownerNo -&gt; oName (D)</p> Signup and view all the answers

What is the result of normalizing the ClientRental relation to 2NF?

<p>Partial dependencies will be resolved by relocating attributes (D)</p> Signup and view all the answers

What is a candidate key in the context of the ClientRental relation?

<p>A minimal set of attributes that can uniquely identify a record (B)</p> Signup and view all the answers

Which statement about the functional dependencies of the ClientRental relation is true?

<p>cName and oName are dependent on different determinants. (B)</p> Signup and view all the answers

What should be done with the attributes that are partially dependent on the primary key during normalization?

<p>Create a new relation containing these attributes and their determinants. (A)</p> Signup and view all the answers

Flashcards

Normalization

Database design technique focused on examining relationships and optimizing attribute grouping.

Functional dependency

A relationship between attributes where the value of one attribute determines the value of another.

Normal Forms

A set of rules that specify how attributes should be grouped into relations to minimize data redundancy and ensure data integrity.

First Normal Form (1NF)

The simplest normal form - eliminates repeating groups within rows (each row has a single value for each attribute).

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Second Normal Form (2NF)

A normal form that builds upon 1NF by requiring that all non-key attributes depend on the entire primary key.

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Third Normal Form (3NF)

The most common normal form used in database design - ensures that all non-key attributes are dependent solely on the primary key and not on any other non-key attribute.

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Normalization process

The process of transforming a database from a lower normal form to a higher normal form.

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Redundant Data

Redundancy that can lead to data inconsistency and problems with data updates.

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Data Redundancy

Data redundancy occurs when the same data is stored in multiple places in a database. This can lead to inconsistencies and inefficiencies.

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Candidate Keys

Candidate keys are sets of attributes that can uniquely identify a row in a table. A primary key is a chosen candidate key.

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Normalization and Data Redundancy

Normalization helps to reduce data redundancy by ensuring that data is only stored once in the database, reducing the risk of inconsistencies and improving data integrity.

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Deletion Anomalies

Deleting a tuple from a relation can accidentally remove information about other entities, leading to data loss.

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Loss of Information

A problem in database design where deleting a tuple affects other related entities unintentionally.

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Normalized Relations

A database design that separates related entities into different tables, minimizing the risk of data loss during deletion.

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Modification Anomalies

Changing the value of an attribute for one member of the relation might require updating multiple tuples, potentially leading to inconsistencies if not done correctly.

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Data Inconsistency

A database design problem where updating a single attribute requires updating multiple records, leading to inconsistencies if not done correctly.

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Decomposition

The process of breaking down a large table into smaller, more manageable tables to address data anomalies.

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Relational Decomposition

Dividing a relation into smaller, related relations to improve data integrity and avoid anomalies.

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Update Anomaly

A state where a database becomes inconsistent due to incomplete updates.

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Transitive dependency

A dependency where a non-key attribute depends on another non-key attribute instead of the primary key.

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Relation Design

The grouping of attributes in a relation, aiming for minimal redundancy and efficient data management.

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Full Functional Dependency

A functional dependency where the left-hand side (determinant) determines the right-hand side, and removing any attribute from the determinant breaks the dependency.

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Partial Functional Dependency

A functional dependency where the left-hand side (determinant) can be reduced to a smaller subset of attributes that still determines the right-hand side.

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Determinant

The attribute(s) on the left-hand side of a functional dependency that determine the value of the attribute(s) on the right-hand side.

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Partial Dependency

A functional dependency where an attribute is dependent on only part of the primary key, not the entire key.

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Full Dependency

A functional dependency where an attribute is dependent on the entire primary key.

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Primary Key

The main key of a relation, used for unique identification of each record.

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When is a relation in 2NF?

A relation is considered to be in 2NF if it is in 1NF and there are no partial dependencies. It means all non-key attributes depend on the entire primary key.

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Non-key Attributes

An attribute that is not part of the primary key.

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Study Notes

Chapter Objectives

  • Normalization is a technique for producing a set of relations with desirable properties, to meet data requirements of an enterprise
  • Relations with data redundancy frequently create update anomalies (insertion, deletion, modification)
  • Functional dependency describes the relationship between attributes. For example, if attribute A and B are in a relationship, B is functionally dependent on A (A → B) if every value of A is associated with exactly one value of B
  • Determinant is the attribute or group of attributes on the left-hand side of the functional dependency arrow
  • The main characteristics of functional dependencies: one-to-one relationship between left and right-hand attributes, validity at all times, and full functional dependency

Unnormalized Form (UNF)

  • A table that contains one or more repeating groups
  • The intersection of each row and column contains one and only one value

First Normal Form (1NF)

  • A relation in which the intersection of each row and column contains a single value
  • Repeating groups are removed

Second Normal Form (2NF)

  • A 1NF relation where every non-primary key attribute is fully functionally dependent on the entire primary key
  • Partial dependencies are removed

Third Normal Form (3NF)

  • A 2NF relation with no transitive dependency on the primary key
  • Transitive dependencies are removed

Boyce-Codd Normal Form (BCNF)

  • Stronger than 3NF
  • Every determinant in a relation is a candidate key

Fourth Normal Form (4NF)

  • A relation with no multi-valued dependency when the determinant is not a candidate key
  • Multi-valued dependencies are removed

Fifth Normal Form (5NF)

  • Addresses the problem of join dependencies
  • Each projection in a relation includes a candidate key of the original relation
  • Lossless-join property is maintained

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Related Documents

Pearson Database Systems: Normalization PDF

Description

This quiz focuses on the key concepts of normalization in database design, including definitions of various normal forms and functional dependencies. It addresses common problems such as data redundancy and the importance of understanding 2NF and 3NF. Test your knowledge of the principles discussed in the normalization chapter.

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