Chapter 3
Which of the following is NOT associated with logical and physical database design?
B) The preparation of a final conceptual model and the implementation of the database
Which of the following properties of a relation states that an entry at the intersection of each row and column is single-valued?
A) Entries in cells are simple.
Which of the following properties should be satisfied when the identifier of the entity type becomes the primary key of the corresponding relation?
A) The value of the key must uniquely identify every row in the relation.
Which of the following is NOT a true statement regarding a relation?
D) Each row in a relation corresponds to an attribute of that relation.
The transformation of an E-R diagram into normalized relations and then the merging of all the relations into one final, consolidated set of relations requires all of the following steps EXCEPT:
D) structure requirements.
The relation state specifying that nonprimary key attributes do not depend on other nonprimary key attributes is:
D) third normal form.
A functional dependency between two (or more) nonkey attributes in a relation defines a:
D) transitive dependency.
Combining all normalized user views into one consolidated logical database model refers to:
D) view integration.
A relation that contains a minimum amount of redundancy and allows users to insert, modify, and delete the rows in a table without errors or inconsistencies is a(n):
D) well-structured relation.
A data model that represents data in the form of tables or relations is called a(n):
C) relational database model.
For any relation R, if, for every valid instance of A, that value of A uniquely determines the value of B:
C) then B is said to be functionally dependent on A.
A binary 1 to many relationship in an ER Diagram is represented by adding the primary key of the entity on the one side of the relationship as a foreign key to the entity on the many side.
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A business rule is an integrity constraint specifying that the value of an attribute in one relation depends on the value of the same attribute in another relation.
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A data marker is a field of data that can be used to locate a related field or row of data.
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A default value is a value a field will assume unless an explicit value is entered for that field.
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A key can be redundant.
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A null value is used to represent the zero digit in a relation.
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A recursive foreign key is a foreign key in a relation that references the primary key value of the same relation.
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A relation corresponds to a computer file.
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A relation is in second normal form if every nonprimary key attribute is functionally dependent on the whole primary key.
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A relation is said to be in second normal form if the primary key consists of a combination key, and the nonkey attributes are partially dependent on the primary key.
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A relation is said to be in second normal form if the primary key consists of only one attribute.
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A relation is said to be in second normal form when there are no transitive dependencies.
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A well-structured relation contains data about two or more entities.
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An attribute can be functionally dependent on more than one attribute.
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Conceptual modeling is performed during systems design.
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Data security can be built into a file through encryption, passwords, or prohibiting users from directly manipulating a file.
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Denormalization is the process of splitting or combining normalized relations into physical tables based on affinity of use of rows and fields.
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Denormalization reduces the chance of errors introduced by normalizing relations.
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Designing the database for an Internet-based electronic commerce application differs significantly from the process followed when designing the database for other types of applications.
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During logic modeling, the normalized data requirements from all user interfaces are combined into one consolidated logical database model.
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During physical database design, relations from logical database design are translated into computer file specifications.
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Each column in a relation corresponds to an entity type.
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Each entity type in an ER Diagram becomes an attribute.
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Each row of a relation corresponds to a record that contains data values for an entity.
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Efficient use of secondary storage and data processing speed are the two goals of physical table design.
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File restoration can be achieved through backup copies of a file, audit trails, and row image files.
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For a binary one-to-one relationship between two entities, A and B, the primary key of A becomes a foreign key in B and the primary key in B becomes a foreign key in A.
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Generally speaking, a physical table corresponds to a relation.
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Generally speaking, logical and physical database design is performed in parallel with other systems design steps.
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If for every valid value of A the value of B is determined by the value of A, then B is functionally dependent on A.
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In general, data structure refers to grouping attributes from the logical database model into physical records.
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Indexes should be used generously for databases intended primarily to support data retrievals.
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Indexes should be used judiciously for databases that support transaction processing and other applications with heavy updating requirements.
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Multiple key retrieval is possible with the hashed file organization.
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Normalization helps build a data model that is simple, not redundant, and requires minimum maintenance.
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Normalization is based on an analysis of weak entities.
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Object-oriented database models are the most frequently used database technologies for new information systems development.
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One of the purposes of logical and physical database design is to choose data-storage technologies that will efficiently, accurately, and securely process database activities.
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One property of a relation is that entries in columns are from the same set of values.
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Random key retrieval on the primary key is comparatively slow with the hashed file organization.
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Referencing a relation, the sequence of columns cannot be interchanged without changing the meaning or use of the relation.
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Referential integrity specifies that the value of an attribute of one relation depends on the existence of the same attribute in another relation.
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Sequential files are practical for random row retrievals.
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Sequential retrieval on the primary key is very fast with the hashed file organization.
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The creation of a separate relation is sometimes required to represent a relationship.
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The hashed file organization determines the address for each row by using an algorithm.
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The network database model is a popular database technology for new information systems.
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The network model is the most common style for a logical database model.
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The result of normalization is that every nonprimary key attribute depends upon the whole primary key and nothing but the primary key.
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The selection of data-storage technologies is made during the systems implementation and operation phase.
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The selection of the appropriate storage format for each attribute from the logical database model is made during physical database design.
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The value of a key attribute in a relation must uniquely identify every row in the relation.
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Transitive attributes are attributes that determine other attributes.
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Two different names used for the same attribute is called a homonym.
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Two different names used for the same attribute is called a synonym.
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View integration is the last step of logical database design.
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When modeling a many-to-many unary relationship, the primary key of the relation representing the relationship is always singular.
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When using the normalized relation notation, the primary key attribute is indicated by a dashed underline.
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When using the sequential file organization, the addition of rows requires rewriting the file.
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Each regular entity type in an E-R diagram is transformed into a:
C) relation.
When two relations, A and B, have a many-to-many relationship, we create a separate relation, C, to represent this.
A corporal key is one assigned by the system.
For a binary many-to-many relationship existing between entity types A and B:
A) a separate relation C is created; the primary key of relation C is a composite key consisting of the primary key for each of the two entities in the relationship.
If an associative entity exists, then:
A) a separate relation C is created; the primary key of relation C is a composite key consisting of the primary key for each of the two entities in the relationship.
An attribute that appears as a nonkey attribute in one relation and as a primary key attribute (or part of a primary key) in another relation is a:
A) foreign key.
If order number serves as the primary key in the order relation and also appears as a nonkey attribute in the invoice relation, then order number is said to be a:
A) foreign key.
The primary deliverable from logical database design is:
A) normalized relations.
The most common style for a logical database model is the:
A) relational database model.
When each nonprimary key attribute is identified by the whole key, the relation is said to be in at least:
A) second normal form.
When transforming an E-R diagram into normalized relations, the identifier of the entity type becomes:
A) the primary key of the corresponding relation.
During logical database design, the work of all systems development team members is coordinated and shared through:
A) the project dictionary.
Which of the following is a purpose of logical and physical database design?
B) Develop a logical database design that reflects the actual data requirements that exist in the forms and reports of an information system.
Which of the following statements is true regarding normalization?
B) Normalization produces a set of well-structured relations that contain all of the data mentioned in system inputs and outputs developed in human interface design.
If a relationship exists among three or more entities, then:
B) a separate relation with a primary key that is the composite of the primary keys of each of the participating entities is created.
A binary one-to-many relationship in an E-R diagram is best represented by:
B) adding the primary key attribute (or attributes) of the entity on the one side of the relationship as a foreign key in the relation that is on the many side of the relationship.
Assume the structure of a relation is Employee (EmpID, Name, Dept, Salary). The number of attributes for this relation would:
B) be four.
A particular relationship between two attributes best defines:
B) functional dependency.
The dependence of nonprimary key attributes on other nonprimary key attributes best describes a:
B) transitive dependency.
A named two-dimensional table of data is a(n):
C) relation.
Which of the following is NOT a key step in logical database modeling and design?
C) Model how data flow through an information system, the relationships among the data flows, and how data come to be stored at specific locations.
Using the normalized relation notation, an attribute of a relation which is the primary key of another relation is indicated by:
C) a dashed underline.
Relationships between instances of a single entity type are referred to as:
C) recursive relationships.
The integrity constraint that specifies that the value (or existence) of an attribute in one relation depends on the value (or existence) of the same attribute in another relation is called:
C) referential integrity.
During physical design, you consider:
E) all of the above.
Key physical database design decisions include:
E) all of the above.
For a binary one-to-one relationship between two entities A and B, the relationship is represented by:
E) either A or B.
For a unary one-to-one relationship between two entities A and B, the relationship is represented by:
E) either A or B.
An entity whose primary key depends on the primary key of another entity is called a:
E) weak entity.
A file organization is an arrangement of related records in secondary memory so that individual and groups of records can be stored, retrieved, and updated rapidly.
The primary deliverable from logical database design is a conceptual model.
The process of converting complex data structures into simple, stable data structures is referred to as:
normalization
