ISM5208 ch1-4 quizes
An entity is a person, place, object, event, or concept in the user environment about which the organization wishes to maintain data.
True
An extranet uses Internet protocols to establish limited access to company data by the company's customers and suppliers.
True
Applications built with a multitier architecture are meant to support departments.
True
Because a purchased data model is extensive, you begin by identifying the parts of the data model that apply to your data modeling situation.
True
Cost and complexity are just two of the disadvantages of database processing.
True
Data from prior systems is converted to the new system during the implementation phase of the systems development life cycle.
True
Data modeling is about documenting rules and policies of an organization that govern data.
True
Data names should always relate to business characteristics.
True
Data structures include data organized in the form of tables with rows and columns.
True
Database maintenance is typically the longest step of the database development process.
True
Enterprise modeling sets the range and general contents of organizational databases.
True
File processing systems have been replaced by database systems in most critical business applications today.
True
In a supertype/subtype hierarchy, attributes are assigned at the highest logical level that is possible in the hierarchy.
True
In an E-R diagram, an associative entity is represented by a rounded rectangle.
True
In practice, databases today may contain either data or information.
True
In prototyping, implementation and maintenance activities are repeated as necessary until the product is correct.
True
Information is processed data.
True
It is easy to miss the opportunity to visualize future requirements shown in the full data model when using a packaged data model.
True
Mapping existing data to new data in a packaged data model is useful for developing migration plans.
True
Metadata are data that describe the properties of other data.
True
One of the major challenges in data modeling is to recognize and clearly represent entities that are almost the same.
True
One property of a relation is that each attribute within a relation has a unique name.
True
One reason to use an associative entity is if the associative entity has one or more attributes in addition to the identifier.
True
Participation in a relationship may be optional or mandatory.
True
Prototyping is a type of rapid application development.
True
Redundancy increases the risk of inconsistent data.
True
Relationships represent action being taken using a verb phrase.
True
Specialization is the reverse of generalization.
True
The E-R model is used to construct a conceptual model.
True
The allowable range of values for a given attribute is part of the domain constraint.
True
Unplanned duplicate data files are the rule rather than the exception in file processing systems.
True
When a regular entity type contains a multivalued attribute, two relations are created.
True
When choosing an identifier, choose one that will not change its value often.
True
In the figure below, the primary key for "Order Line" is which type of key?
Composite
A cardinality constraint tells what kinds of properties are associated with an entity.
False
A composite key consists of only one attribute.
False
A constraint is a rule in a database system that can be violated by users.
False
A foreign key is a primary key of a relation that also is a primary key in another relation.
False
A member of a subtype does NOT necessarily have to be a member of the supertype.
False
A relation is in first normal form if it has no more than one multivalued attribute.
False
A subtype is a generic entity that has a relationship with one or more entities at a lower level.
False
A ternary relationship is equivalent to three binary relationships.
False
A transversal dependency is a functional dependency between two or more nonkey attributes.
False
A user view is how the user sees the data when it is produced.
False
A well-structured database establishes the entities between relationships in order to derive the desired information.
False
An enterprise data model describes the scope of data for only one information system.
False
CASE tools can model more complex data relationships, such as ternary relationships.
False
Creating a data model from a packaged data model requires much more skill than creating one from scratch.
False
Data redundancy is used to establish relationships between data but is never used to improve database performance.
False
Database processing programs are coded and tested during the design stage of the systems development life cycle.
False
Databases were developed as the first application of computers to data processing.
False
In 1998, ANSI/SPARC published an important document describing the three-schema architecture.
False
In an E-R diagram, strong entities are represented by double-walled rectangles.
False
In the relational data model, associations between tables are defined through the use of primary keys.
False
Most systems developers believe that data modeling is the least important part of the systems development process.
False
Personal databases are designed to support a small group of individuals working together on a project.
False
Reduced program maintenance is an advantage of file processing systems.
False
Subtypes at the lowest level of a hierarchy do not inherit attributes from their ancestors.
False
Supertype/subtype relationships should be used when the instances of a subtype participate in no relationships which are unique to that subtype.
False
The degree of a relationship is the number of attributes that are associated with it.
False
The disjoint rule specifies that if an entity instance of the supertype is a member of one subtype, it MUST simultaneously be a member of another subtype.
False
The entity integrity rule states that a primary key attribute can be null.
False
The intent of a business rule is to break down business structure.
False
The physical structure and storage organization of the database are decided upon during the implementation phase of the systems development life cycle.
False
The primary key of the many side migrates to the one side when transforming a one-to-many relationship.
False
The relational data model does, at this time, directly support subtype/supertype relationships.
False
The relationship among the instances of three entity types is called a unary relationship.
False
The steps of the systems development life cycle can only be viewed as a linear process.
False
The term legacy system refers to a newly installed database management system.
False
The total specialization rule states that an entity instance of a supertype is allowed not to belong to any subtype.
False
The truncate table statement in SQL creates a new table.
False
There are three separate discriminators in the following diagram because of the overlap rule.
False
There can be multivalued attributes in a relation.
False
When the total specialization rule is set for a supertype/subtype relationship, one could roughly compare the supertype to an abstract class in object-oriented programming.
False
When transforming a one-to-one relationship, a new relation is always created.
False
When transforming a unary many-to-many relationship to relations, a recursive foreign key is used.
False
When transforming a weak entity, one should create one relation with both the attributes of the strong entity and the attributes of the weak entity.
False
A business rule is a statement that defines or constrains some aspect of the business.
True
A candidate key is an attribute, or combination of attributes, that uniquely identifies a row in a relation.
True
A cascading delete removes all records in other tables associated with the record to be deleted.
True
A completeness constraint may specify that each entity of the supertype must be a member of some subtype in the relationship.
True
A good data definition is always accompanied by diagrams, such as the entity-relationship diagram.
True
A partial functional dependency is a functional dependency in which one or more nonkey attributes are functionally dependent on part (but not all) of the primary key.
True
If an identifier is not assigned, the default primary key for an associative relation consists of the two primary key attributes from the other two relations.
True
The most common way to support a group of individuals who work together on a project or group of similar projects is with a two-tier client/server database.
True
The overlap rule specifies that if an entity instance of the supertype is a member of one subtype, it can simultaneously be a member of two (or more) subtypes.
True
The relationship between a weak entity type and its owner is an identifying relationship.
True
The repository is populated during the analysis phase of the systems development life cycle.
True
The systems development life cycle is the traditional methodology used to develop, maintain, and replace information systems.
True
View integration is the process of merging relations together.
True
When normalizing, the goal is to decompose relations with anomalies to produce smaller, well-structured relations.
True
The purpose of data modeling is to document business rules about processes.
False
Unlike columns, the rows of a relation may not be interchanged and must be stored in one sequence.
False
When subtypes are overlapping, an additional field must be added to the supertype to act as a discriminator.
False
With the traditional file processing approach, each application shares data files, thus enabling much data sharing.
False
You will never need to map data in current databases to data in a packaged data model.
False
An attribute whose values can be calculated from related attribute values is called a derived attribute.
True
An entity instance of a subtype represents the same entity instance of the supertype.
True
All values that appear in a column of a relation must be taken from the same domain.
True
Data integrity consists of powerful operations to manipulate data stored in relations.
False
Generalization is a top-down process.
False
A multivalued attribute may take on more than one value for a particular entity instance.
True
A physical schema contains the specifications for how data from a conceptual schema are stored in a computer's secondary memory.
True
A primary key is an attribute that uniquely identifies each row in a relation.
True
A referential integrity constraint is a rule that maintains consistency among the rows of two relations.
True
A relational database establishes the relationships between entities by means of a common field.
True
A single occurrence of an entity is called an entity instance.
True
A subtype can become a supertype if the subtype has other subtypes beneath it.
True
A time stamp is a time value that is associated with a data value.
True
A universal data model is a generic or template data model that can be reused as a starting point for a data modeling project.
True
A well-structured relation contains minimal redundancy and allows users to manipulate the relation without errors or inconsistencies.
True