IS 385 Ch 9
Which of the following statements is true regarding normalization? A) Normalization produces a set of well-structured relations that contain all of the data mentioned in system inputs and outputs. B) Through the use of anomalies, stable structures are produced. C) Normalization is a top-down process. D) Normalization 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.
A) Normalization produces a set of well-structured relations that contain all of the data mentioned in system inputs and outputs.
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. B) The key must be a composite of a primary key and a secondary key. C) The key should serve as a foreign key in at least two other relations. D) The key should be an intelligent key.
A) The value of the key must uniquely identify every row in the relation.
Each regular entity type in an E-R diagram is transformed into a: A) relation B) row in a relation C) column in a relation D) tuple in a relation
A) relation
The relation state specifying that non primary key attributes do not depend on the non primary key attributes is: A) Boyce-Codd normal form B) third normal form C) first normal form D) second normal form
B) third normal form
If an associative entity exists, then: A) place the primary key of either entity in the relation for the other entity or do this for both entities B) secondary keys are used to establish the relationship C) 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 D) the primary keys of relation A and relation B are designated as functionally dependent attributes.
C) 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
To convert a relation to second normal form, you decompose the relation into new relations using the attributes, called: A) relationship key B) foreign key C) determinants D) pointer
C) determinants
For any relation R, if, for every valid instance of A, that value of A uniquely determines the value of B: A) then A is said to be functionally dependent on B B) then a primary dependency exists in the relation C) the A and B are candidate keys for the relation D) the B is said to be functionally dependent on A
D) the B is said to be functionally dependent on A
A functional dependency between two (or more) non primary key attributes in a relation defines a: A) weak dependency B) partial dependency C) simpe dependency D) transitive dependency
D) transitive dependency
A relation corresponds to a computer file.
False
A relation is said to be in second normal form when its non primary key attributes do not depend on each other.
False
A relation is said to be in second normal form when there are no transitive dependencies.
False
A well-structured relation contains data about two or more entities.
False
Conceptual modeling is performed during systems design.
False
Denormalization reduces the chance of errors introduced by normalizing relations.
False
During logic modeling, the data requirements from all user interfaces are combined into one consolidated logical database model.
False
Each column in a relation corresponds to an entity type.
False
Generally speaking, a physical table corresponds to a relation.
False
Multiple key retrieval is possible with the hashed file organization.
False
Normalization is based on an analysis of weak entities.
False
Object-oriented database models are the most frequently used database technologies for new information systems development.
False
Referencing a relation, the sequence of columns cannot be interchanged without changing the meaning or use of the relation.
False
Sequential files are practical for random row retrievals.
False
Sequential retrieval on the primary key is very fast with the hashed file organization.
False
The network model is the most common style for a logical database model.
False
The primary deliverable from logical database design is a conceptual model.
False
The selection of data storage technologies is made during the systems implementation and operation phase.
False
A physical file is a named set of table rows stored in a contiguous section of secondary memory.
True
A relation is in second normal form if every non primary key attribute is functionally dependent on the whole primary key.
True
A relation is said to be in second normal form if the primary key consists of only one attribute.
True
An attribute can be functionally dependent on more than attribute.
True
Data security can be built into a file through encryption, passwords, or prohibiting users from directly manipulating a file.
True
Denormalization is the process of splitting or combining normalized relations into physical tables based on affinity of use of rows and fields.
True
During physical database design, relations from logical database design are translated into computer file specifications.
True
Each row of a relation corresponds to a record that contains data values for an entity.
True
Efficient use of secondary storage and data processing speed are the two goals of physical table design.
True
File restoration can be achieved through backup copies of a file, audit trails, and row image files.
True
Generally speaking, logical and physical database design is performed in parallel with other systems design steps.
True
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.
True
In general, data structure refers to grouping attributes from the logical database model into physical records.
True
Indexes should be used generously for databases intended primarily to support data retrievals.
True
One of the purposes of database design is to choose data storage technologies that will efficiently, accurately, and securely process database activities.
True
The creation of a separate relation is sometimes required to represent a relationship.
True
The selection of the appropriate storage format for each attribute from the logical database model is made during physical database design.
True
When using the sequential file organization, the addition of rows requires rewriting the file.
True
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. b. Entries in columns are from the same set of values. c. Each row is unique. d. The sequence of rows is insignificant.
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. b. The key should serve as a foreign key in at least two other relations. c. The key must be a composite of a primary key and a secondary key. d. The key should be an intelligent key.
a. The value of the key must uniquely identify every row in the relation.
the primary key of relation C is a composite key consisting of the primary key for each of the two entities in the relationship a. a separate relation C is created b. the primary keys of relation A and relation B are designated as functionally dependent attributes c. secondary keys are used to establish the relationship d. place the primary key of either entity in the relation for the other entity or do this for both entities
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 a. a separate relation C is created b. the primary keys of relation A and relation B are designated as functionally dependent attributes c. secondary keys are used to establish the relationship d. place the primary key of either entity in the relation for the other entity or do this for both entities
a. a separate relation C is created
An attribute that appears as a nonprimary key attribute in one relation and as a primary key attribute (or part of a primary key) in another relation is a: a. foreign key b. candidate key c. pointer d. relationship key
a. foreign key
If order number serves as the primary key in the ORDER relation and also appears as a nonprimary key attribute in the INVOICE relation, then order number is said to be a: a. foreign key b. candidate key c. pointer d. relationship key
a. foreign key
The process of converting complex data structures into simple, stable data structures is referred to as: a. normalization b. simplification c. structuring d. process modeling
a. normalization
The primary deliverable from logical database design is: a. normalized relations b. design specifications c. an updated baseline project plan d. a list of alternatives design strategies
a. normalized relations
A field of data that can be used to locate a related field or row of data best describes: a. pointer b. marker c. field locator d. reference locator
a. pointer
The most common style for a logical database model is the: a. relational database model b. hierarchical database model c. network database model d. object-oriented database model
a. relational database model
When transforming an E-R diagram into normalized relations, the identifier of the entity type becomes: a. the primary key of the corresponding relation b. the foreign key in the corresponding relation c. a nonkey attribute in the corresponding relation d. a secondary key in the corresponding relation
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 b. scheduled weekly meetings c. the project leader d. JAD sessions
a. the project dictionary
Merging relations is also referred to as: a. view integration b. view consolidation c. encompassing d. normalizing
a. view integration
A relation that contains a minimum amount of redundancy and allows users to insert, modify, and delete rows without errors or inconsistencies is a(n): a) simple relation b) well-structured relation c) independent relation d) unnormalized relation
b) well-structured relation
Which of the following statements is true regarding normalization? a. Normalization is a top-down process. b. Normalization produces a set of well-structured relations that contain all of the data mentioned in system inputs and outputs. c. Through the use of anomalies, stable structures are produced. d. Normalization 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.
b. Normalization produces a set of well-structured relations that contain all of the data mentioned in system inputs and outputs.
Which of the following is not associated with database design? a. Structure the data in stable structures that are not likely to change over time and that have minimal redundancy. b. The preparation of a final conceptual model and the implementation of the database. c. Develop a logical database design from which we can do physical database design. d. Develop a logical database design that reflects the actual data requirements that exist in the forms and reports of an information system.
b. The preparation of a final conceptual model and the implementation of the database.
If a relationship exists among three or more entities, then: a. recursive relationships must be established through the use of recursive foreign keys b. a separate relation with a primary key that is the composite of the primary keys of each of the participating entities is created c. separate relations are established for each class and for each of the subclasses d. use the primary key of relation A as a foreign key in relations B and C
b. a separate relation with a primary key that is the composite of the primary keys of each of the participating entities is created
the primary key of this new relation is a composite key consisting of the primary key for each of the two entities in the relationship 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 c. adding the primary key attribute (or attributes) of the entity on the many side of the relationship as a foreign key in the relation that is on the one side of the relationship d. creating a relation with a composite primary key and monkey attributes
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
A many-to-many relationship that associates certain items with their component items is called a: a. binary structure b. bill-of-materials structure c. binary relationship d. ternary relationship
b. bill-of-materials structure
A particular relationship between two attributes best defines: a. context b. functional dependency c. normal form d. structure
b. functional dependency
A foreign key in a relation that references the primary key values of that same relation is referred to as a: a. secondary key b. recursive foreign key c. composite key d. complex key
b. recursive foreign key
"Create a relation with primary key and nonkey attributes" is the relational representation for which E-R structure? a. weak entity b. regular entity c. gerund d. IS-A relationship
b. regular entity
Combining all normalized user views into one consolidated logical database model refers to: a. requirements structuring b. view integration c. normalization d. file integration
b. view integration
The primary deliverable from logical database design is: a) a list of alternative design strategies b) an updated baseline project plan c) normalized relations d) design specifications
c) normalized relations
Which of the following is not a key step in logical database modeling and design? a. Combine normalized data requirements from all user interfaces into one consolidated logical database model. b. Compare the consolidated logical database design with the translated E-R model and produce, through view integration, one final logical database design for the application. 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. d. Translate the conceptual E-R data model for the application into normalized data requirements.
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 relational notation, an attribute of a relation that is the primary key of another relation is indicated by: a. an underline b. a circle c. a dashed underline d. italics
c. a dashed underline
A table used to determine the location of rows in a file that satisfy some condition best describes: a. relation b. structure chart c. index d. domain table
c. index
A special field value, distinct from 0, blank, or any other value, that indicates that the value for the field is missing or otherwise unknown best defines: a. transitive value b. primary key c. null value d. pointer
c. null value
The index file organization: a. provides very fast random retrieval on the primary key b. provides slow random retrieval on the primary key c. provides moderately fast random retrieval on the primary key d. does not provide random retrieval on the primary key
c. provides moderately fast random retrieval on the primary key
Relationships between instances of a single entity type are referred to as: a. binary relationships b. transitive relationships c. recursive relationships d. dependent relationships
c. recursive relationships
A named two-dimensional table of data is a: a. network b. tree structure c. relation d. tuple
c. relation
A data model that represents data in the form of tables or relations is called a: a. hierarchical database model b. network database model c. relational database model d. hybrid database model
c. relational database model
When two 3NF relations are merged to form a single relation: a. weak entities are created b. recursive relationships may result c. transitive dependencies may result d. IS-A relationships are formed
c. transitive dependencies may result
When each non primary key attribute is identified by the whole key, the relation is said to be in at least: a) fifth normal form b) fourth normal form c) third normal form d) second normal form
d) second normal form
Which of the following is not a true statement regarding a relation? a. Each relation consists of a set of named columns and an arbitrary number of unnamed rows. b. Each column in a relation corresponds to an attribute of that relation. c. An entry at the intersection of each row and column has a single value. d. Each row in a relation corresponds to an attribute of that relation.
d. Each row in a relation corresponds to an attribute of that relation.
During physical design, you consider: a. the definitions of each attribute b. the descriptions of where and when data are entered, retrieved, deleted, and updated c. the expectations for response time and data integrity d. all of the above
d. all of the above
Key physical database design decisions include: a. choosing the storage format for each attribute from the logical database model b. grouping attributes from the logical database model into physical records c. arranging related records in secondary memory so that individual and groups of records can be stored, retrieved, and updated rapidly d. all of the above
d. all of the above
For a binary one-to-one relationship between two entities A and B, the relationship is represented by: a. adding the primary key of A as a foreign key of B b. adding the primary key of B as a foreign key of A c. combining the two entities into one relation d. either a or b
d. either a or b
For a unary one-to-one relationship between two entities A and B, the relationship is represented by: a. adding the primary key of A as a foreign key of B b. adding the primary key of B as a foreign key of A c. combining the two entities into one relation d. either a or b
d. either a or b
A named set of rows and columns that specifies the fields in each row of the table best describes: a. relation b. data structure c. entity type d. physical table
d. physical table
An entity whose primary key depends on the primary key of another entity is called a: a. referential entity b. candidate entity c. transitive entity d. weak entity
d. weak entity