Test 1 Flashcards
Disjoint subtypes are also known as ____ subtypes
non-overlapping
Specialization is based on grouping ____ characteristics and relationships of the subtypes.
unique
Usually, a data modeler uses a natural identifier as the ____ of the entity being modeled, assuming that the entity has a natural identifier
Primary key
Unique values can be better managed when they are _____, because the database can use internal routines to implement a counter-style attribute that automatically increments values with the addition of each new row
numeric
composite primary keys are particularly useful as identifiers of composite entities, where each Primary key combination is allowed____in the M:N relationship.
once
Composite keys are useful as identifiers of weak entities, where the weak entity has a strong___ relationship with the parent entity.
identifying
One practical advantage of a(n) ____key is that because it has no intrinsic meaning, values for it can be generated by the DBMS to ensure that unique values are always provided.
surrogate
While using a surrogate key, one must ensure that the candidate key of the entity in question performs properly through the use of the “___” and “not null” constraints.
unique index
From a data modeling point of view, ____ data refer to data who’s values change over time and for which one must keep a history of the data changes.
Time-variant
The main concern with redundant relationships is that they remain____across the model
consistent
____ are characteristics of entities
Attributes
A(n)____ attribute is an attribute that must have a value
required
A person’s Social Security number would be an example of a(n)____ attribute
single-valued
a(n)____attribute need not be physically stored within the database
derived
When indicating cardinality, the first value represents the ____ number of associated entities
minimum
The concept of relationship strength is based on how the ____ of a related entity is defined.
primary key
A(n) ____ relationship is also known as an identifying relationship.
strong
A weak entity must be ____-dependent
existence
The Chen notation identifies a weak entity by using a double-walled entity
rectangle
Participation is____ if one entity occurrence does not require a or responding entity occurrence in a particular relationship.
optional
A table is also called a (n)____ because the relational model’s creator, E.F. Codd use the two terms as synonyms.
relation
in a relational table, each column has a specific range of values known as the _____domain.
attribute
in a relational model, ____ are also used to establish relationships among tables and to ensure the integrity of the data.
keys
A primary key is the____key chosen to be the primary means by which rows of a table are uniquely identified.
candidate
To avoid nulls, some designers use special codes, known as _____, to indicate the absence of some value.
flags
The relational operators have the property of ____; that is, the use of relational algebra operators on existing relations (tables) produces new relations.
closure
PRODUCT yields all possible pairs of rows from two tables, also known as the ____ product
Cartesian
____ is the real power behind the relational database, allowing the use of independent tables linked by common attributes
JOIN
A(n) ____links tables on the basis of an equality condition that compares specified columns of each table.
equijoin
A(n) ____ provides a detailed description of all tables in the database created by the user and designer.
data dictionary
___ is the result of processing raw data to reveal its meaning.
Information
to reveal meaning, information requires____
context
Information is produced by processing___.
data
____ is data about data through which the end-user data are integrated and managed
Metadata
A(n)_____ is a specific request issued to the DBMS for data manipulation.
query
____databases focuses primarily on storing historical data and business metrics used exclusively for tactical or strategic decision making.
Analytical
____ is a special language used to represent and manipulate data elements in a textual format.
XML(Extensible Markup Language)
A(n) ____ is a spur-of-the-moment question
ad hoc query
___exists when different versions of the same data appear in different places.
Data inconsistency
____exists when the same data are stored unnecessarily at different places.
Data redundancy
A process that focuses on data collection, storage, and retrieval. Common______ _____ functions include addition, deletion, modification, and listing
Data Management
The process that yields the description of the database structure and determines the database componenets. ______ ______ is the second phase of the database life cycle
Database Design
The collection of programs that manages the database
Database Management System (DBMS)
51- ____ is used to reveal the meaning of data
Information
68-In the relational model, _____ are important because they are used to insure that each row in a table is uniquely identifiable.
keys
14- you can think of a table as a persistent representation of a logical relation
True
A minimal superkey; that is, a key that does not contain a subset of attributes that is itself a superkey
Candidate key
a primary key can be made up of one or more attributes
True
88-an entity cluster is formed by combining multiple interrelated entities into _____
a single abstract entity
75-Some attributes are classified as _____
simple
A constraint that specifies whether each entity supertype occurrence must also be a member of at least one subtype. The ______ _______ can be partial or total.
Completeness constraint
______means that some supertype occurrences might not be members of any subtype
Partial completeness
___means that every supertype occurrence must be a member of at least one subtype.
Total completeness
Aproblem that occurs when a realtionship is improperly or incompletely identified and therfor is represented in a waay that is not consistent with the real world. The most common ___ ___ is know as a fan trap
Design Trap
The ____ ____ ____ resulting from the application of extended entity realitonsip concepts that proved additional semantic content in the er model
EER diagram
A virtual entity type used to represent multiple entites and relationships in the erd and ___ ___ is formed by combining multiple interrelated entities into a single abstract entity in the final erd
entity cluster
In a genreralization/ specialization hierarchy a subset of an entity supertyp. the ____ _____ contains the common characteriscs of entity subtypes
Entity supertype
The result of adding more semantic constructs, such as entity supertypes, entity subtypes and entity clustering, to the original entity relationship model
Exentended entity relationship model (eerm)
In the object-oreiented data model, the ability of an object to inherit the data sturctue and mehtods of theclasses above it in the class hierarchy
Inheritance
A generallly accepted identifier for real0world objects. as its name implies an ___ ___ is a familiiar to end users and forms part of ther day-to-day business vocab
Natural Key
in a generalization hierarrchy, a condition in which some supertype ocurrences might not be members of any subtype
Partial completeness
the grouping of unique attribute into a sub types entity
Specialization
an entity that coontains unique characteristics within a more broadly defined enntity known as a supertype
subtype
___ ___ an er term for an association between two entities.
Binary relationship
__ ____ an attribute that can be further subdivieded to yeild additional attributes
Composite attribute
In er modley a key composed of more than one attribute.
Composite identifier
a reltionship in which related entities are existence-dependent.
Identifying relatinoship
A process based on repeitiion of steps and procedures
Iterative process
a relationship in which one entity occurence must have a corresponding occurence in another entity
Mandatory participation
and attribute that can ahve many values for a single entity occurence
Multivalued attributes
A relationship in which the primary key of the dependent entity does not conatina the primary key of the related parent entity
Non-identifying relationship
in er modelinng an attribute that does not requier a vlaue
optional attribute
the organization of a relational database as described by the database administrator
Relational schema
The number of entites or participatns assciated with a relationship
Relationship degree
