Modern Database Management – Self Check 02 – Flashcards
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A ________ is a statement that defines or constrains some aspect of the business.
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business rule
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A ________ is an association between two or more terms.
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fact
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A ________ may be associated with any data value that changes over time when we need to maintain a history of those data values.
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time stamp
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A ________ relationship occurs between two instances of a single entity type.
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unary
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A ________ specifies the number of instances of one entity that can be associated with each instance of another entity.
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cardinality constraint
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A business rule is a statement of how a policy is enforced or conducted
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False
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A business rule is a statement that defines or constrains some aspect of the business.
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True
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A business rule should be internally consistent.
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True
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A cardinality constraint tells what kinds of properties are associated with an entity.
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False
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A fact is an association between two or more terms.
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True
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A good data definition is always accompanied by diagrams, such as the entity-relationship diagram
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True
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A logical representation of the data for an organization or for a business area is called a(n) ________.
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entity-relationship model
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A meaningful relationship between entity types is called a(n) ________.
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relationship type
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A multivalued attribute may take on more than one value for a particular entity instance.
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True
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A property or characteristic of an entity is a(n) ________.
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attribute
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A relationship instance is an association between entity instances where each relationship instance includes exactly one entity from each participating entity type.
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False
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A relationship name is a ________.
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verb phrase
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A simple attribute can be broken down into smaller pieces.
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False
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A simultaneous relationship among the instances of three entity types is called a ________ relationship.
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ternary
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A single occurrence of an entity is called an entity instance.
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True
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A single occurrence of an entity type is called an entity ________.
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instance
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A ternary relationship is equivalent to three binary relationships.
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False
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A time stamp is a time value that is associated with a data value.
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True
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A weak entity type is related to its owner by a(n) ________
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identify relationship
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A(n) ________ entity type exists independently of other entity types.
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strong
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A(n) ________ is an attribute that uniquely identifies individual instances of an entity type.
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identifier
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An affirmative entity is also called a relationship entity.
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False
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An attribute that can be broken down into component parts is called a(n) ________ attribute.
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composite
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An attribute whose value can be calculated from a related attribute is called a(n) ________ attribute.
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derived
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An attribute whose values can be calculated from related attribute values is called a derived attribute.
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True
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An entity is a person, place, object, event, or concept in the user environment about which the organization wishes to maintain data.
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True
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An entity type name should always be a singular noun.
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True
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An entity type on which a strong entity is dependent is called a covariant entity.
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False
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An entity type that associates the instances of one or more entity types and contains attributes that are peculiar to the relationship is called a(n) ________.
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associative entity
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An entity-type name should be ________ to the organization.
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specific
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An example of a term would be the following sentence: "A student registers for a course."
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F.... Bawls
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An identifier should be chosen that has valid values and is not ________.
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null
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Business rules are formulated from a collection of business ramblings.
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False
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Data names do not have to be unique.
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False
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Data names should always relate to business characteristics.
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True
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Data rather than processes are the most complex aspects of many modern information systems
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True
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Enforcement of business rules can be automated through the use of software tools that can interpret the rules and enforce them.
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True
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In an E-R Diagram, an associative entity is represented by a rounded rectangle.
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True
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In an E-R Diagram, strong entities are represented by double-walled rectangles.
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False
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In the figure below, one might want to create a single-attribute surrogate identifier to substitute for the composite identifier.
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False
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In the figure below, the name of the relationship follows the guidelines for naming a relationship.
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False
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It is desirable that no two attributes across all entity types have the same name.
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True
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It is not permissible to associate attributes with relationships.
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False
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Most systems developers believe that data modeling is the least important part of the systems development process.
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False
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One of the roles of a database analyst is to identify and understand rules that govern data.
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True
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One reason to use an associative entity is if the associative entity has one or more attributes in addition to the identifier.
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True
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Participation in a relationship may be optional or mandatory.
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True
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Relationships represent action being taken using a verb phrase.
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True
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Some examples of attributes are: eye_color, weight, student_id, student.
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False
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The E-R model is used to construct a conceptual model.
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True
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The degree of a relationship is the number of attributes that are associated with it.
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False
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The intent of a business rule is to break down business structure.
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False
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The maximum criminality of a relationship is the maximum number of instances of entity B that may be associated with each instance of entity A.
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False
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The name used for an entity type should never be the same in other E-R diagrams on which the entity appears.
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False
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The number of entity types that participate in a relationship is called the ________ of the relationship.
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degree
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The purpose of data modeling is to document business rules about processes.
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False
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The relationship among the instances of three entity types is called a unary relationship.
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False
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The relationship between a weak entity type and its owner is an identifying relationship.
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True
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The relationship between the instances of two entity types is called a binary relationship.
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True
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When choosing an identifier, choose one that will not change its value often.
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True
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When systems are automatically generated and maintained, quality is diminished.
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False
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While business rules are not redundant, a business rule can refer to another business rule.
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True
