184 terms

Data Modeling Foundations

Mid-Term Review Chapters 1 - 5
____ is used to reveal the meaning of data.
Good decision making
Accurate, relevant, and timely information is the key to ___.
row facts of interest to the end-user
End-user data is _____.
____ provides a description of the data characteristics and the set of relationships that link the data found within the database.
The ____ serves as the intermediary between the user and the database.
application program
A(n) ____ might be written by a programmer or it might be created through a DBMS utility program.
query result set
The response of the DBMS to a query is the ____.
A(n) ____ database is designed to support a company's day-to-day operations.
A(n) ___ database is used by an organization and supports many users across many departments.
A workgroup database is a(n) ___ database.
operational databases
Most decision-support data are based on historical data obtained from ___.
____ data exist in the format in which they were collected.
____ data exist in a format that does not lend itself to processing that yields information.
____ data are the result of formatting to facilitate storage, use and generation of information.
Most data you encounter is best classified as ____.
Which of the following is an example of structured data?
XML data is ____.
A ___ is a logically connected set of one or more fields that describes a person, place or thing.
A ____ is a collection of related records.
A(n) ______'s main function is to help you understand the complexities of the real-world environment.
A(n) ___ represents a particular type of object in the real world.
A(n) ___ is anything about which data are to be collected and stored.
A(n) ___ is equivalent of a field file system.
A(n) ___ is bidirectional.
A(n) ____ is a restriction placed on the data.
___ are important because they help to ensure data integrity.
___ are normally expressed in the form of rules.
many to many
Students and classes have a ___ relationship.
a detailed description of organization operations
business rules are derived from ___.
serve as a communication tool between the users and designers
Which of the following is true of business rules?
A noun in a business rule translates to a(n) ___ in the data model.
A verb associating two nouns in a business rule translates to a(n) ___ in the data model.
The hierarchical data model was developed in the ____.
The object oriented data model was developed in the ____.
file system data model
VMS/VSAM is an example of a(n) _____.
XML/Hybrid data model
Oracle 11g is an example of a(n) _____.
relational data model
MySQL is an example of
a(n) _____.
In the ___ model, the basic logical structure is represented as an upside-down tree.
In the ___ model, each parent can have many children, but each child has only one parent.
The relational data model was developed in the ____.
In the ___ model, the user perceives the database as a collection of records in 1:M relationships, where each record can have more than one parent.
(DDL) data definition language
A(n) _____ enables a database administrator to define schema components.
entity relationship
The ____ model was developed to allow designers to use a graphical tool to examine structures rather than describing them with text.
entity relationship
The ___ model uses the term connectivity to label the relationship types.
The ___ data model is said to be a semantic data model.
The ___ data model uses the concept of inheritance.
One of the limitations of the ____ model is that there is a lack of standards.
The ___ model is the end users' view of the data environment.
A(n) ____ model represents a global view of the database as viewed by the entire organization.
logically, physically
The relational database model enables you to view data ___ rather than ____.
A(n) ____ is perceived as a two-dimensional structure composed of rows and columns.
Date Attributes contain calendar dates stored in a special format known as the ___ date format.
In the context of a database table, the statement "A___B" indicates that if you know the value of attribute A, you can look up the value of attribute B.
functionally dependent on
The attribute B is ___ the attribute A if each value in column A determines one and only one value in column B.
A ___ is any key that uniquely identifies each row.
No data entry at all is known as a ___.
Controlled ___ makes a relational database work.
A ___ key is defined as a key that is used strictly for data retrieval purposes.
A ___ key can be described as a superkey without unnecessary attributes, that is, a minimal superkey.
not null
The ___ constraint can be placed on a column to ensure that every row in the table has a value for that column.
To be considered minimally relational, the DBMS must support the key relational operators ____, PROJECT and JOIN.
____, also known as RESTRICT, yields values for all rows found in a table that satisfy a given condition.
____ yields a vertical subset of a table.
___ combines all rows from two tables, excluding duplicate rows.
____ yields only the rows that appear in both tables.
A(n) ____ join links tables by selecting only the rows with common values in their common attribute(s).
The equijoin takes its name from the comparison operator ___used in the condition.
A(n) ____ join only returns matched records from the tables that are being joined.
data dictionary
A ___ contains at least all of the attribute names and characteristics for each table in the system.
system catalog
The ___ is actually a system-created database whose tables store the user/designer-created database characteristics and contents.
In a database context, a(n) ___ indicates the use of different names to describe the same attribute.
The ___relational type is the "relational model ideal."
The ___ relationship should be rare in any relation database design.
Another name for a composite entity is a ___ entity.
A(n) ____ is an ordered arrangement of keys and pointers.
When you define a table's primary key, the DBMS automatically creates a(n) ___ index on the primary key
column(s) you declared.
logical data independence
Codd's Rule of ___ states: Application programs & ad hoc facilities are logically unaffected when changes are made to the table structures that preserve the original table values (changing order of columns or inserting columns.)
Codd's Rule of ___ states: If the system supports low-level access to the data, users must not be allowed to bypass the integrity rules of the database.
The ERD represents the ___ database as viewed by the end user.
Some ___ database modeling concepts can be expressed only using the Chen notation.
Attributes may share a ____.
The set of possible values for an attribute is a ___.
In an ER diagram, primary keys are indicated by ___.
Ideally, an entity identifier is composed of ___ attributes.
A ___ identifier is composed of more than one attribute.
A ___ attribute can be further subdivided to yield additional attributes.
A ___ attribute is one that cannot be subdivided.
A ____ attribute can have only one value.
____ attributes can have many values.
Some attributes are classified as _____.
Although the conceptual model can handle ____ relationships and multivalued attributes, you should not implement them in the RDBMS.
person's age
A ___ should be a derived attribute.
need not be stored physically
A derived attribute ____.
dashed line
A derived attribute is indicated in the Chen model by a ____.
A relationship is an association between ____.
maximum & minimum
Knowing the ___ number of entity occurrences is very helpful at the application software level.
(min, max)
In the ERD, cardinality is indicated using the ____ notation.
Another word for existence-independent is ____.
An entity is said to be ___-dependent if it can exist in the database only when it is associated with another related
If an entity can exist apart from one or more related entities, it is said to be ____-independent.
When the PK of one entity does not contain the PK of a related entity, the relationship is ____.
A ____ entity has a primary key that is partially or totally derived from the parent entity in the relationship.
The term ____ is used to label any condition in which one or more optional relationships exist.
The existence of a(n) ____ relationship indicates that the minimum cardinality is at least 1 for the mandatory entity.
(1, 1)
The Crow's foot symbol with two parallel lines indicates ____ cardinality.
A ___ relationship exists when two entities are associated.
A ___ relationship exists when an association is maintained within a single entity.
A ___ relationship exists when three entities are associated.
____ relationships are most common.
If an employee within an EMPLOYEE entity has a relationship with itself, that relationship is known as a ___ relationship.
A(n) ____ entity is composed of the primary keys of each of the entities to be connected.
The associative entity is also known as a ___ entity.
detailed narrative of the organizations description of operations
The following step occurs first in the process of building an ERD: ____.
If Tiny College had some departments that were classified as "research only," they would not offer courses; therefore, the COURSE entity would be ___ to the DEPARTMENT entity.
The M:N relationship between STUDENT and CLASS must be divided into two 1:M relationships through the use of the ENROLL entity; the ENROLL entity is ____.
If the focus is on data-retrieval speed, you might also be forced to include ___ attributes in the design, which would not ordinarily be done.
Complex ___ requirements may dictate data transformations, and they may expand the number of entities and attributes within the design.
enhanced entity relationship model
The extended entity relationship model (EERM) is sometimes referred to as the ___.
An entity supertype
____ is a generic entity type that is related to one or more entity subtypes.
specialization hierarchy
The ___ depicts the arrangement of higher-level entity supertypes (patient entities) and lower-level entity subtypes.
only one
Within a specialization hierarchy, every subtype can have ___ supertype to which it is directly related.
A specialization hierarchy can have ___ levels of supertype relationships.
The property of ___ enables an entity subtype to inherit the attributes and relationships of the the supertype.
One important inheritance characteristic is that all entity subtypes inherit their ___ key attribute from their supertype.
at the implementation level, the supertype and its subtypes depicted in the specialization hierarchy maintain a ___ relationship.
subtype discriminator
A ___ is the attribute in the supertype entity that determines to which entity subtype each supertype occurrence is related.
The default comparison condition for the subtype discriminator attribute is the ___ comparison.
non-overlapping subtypes are subtypes that contain a ___ subset of the supertype entity set.
Overlapping subtypes are subtypes that contain ___ subsets of the supertype entity set.
circle over a single line
Partial completeness is symbolized by ___.
is the bottom-up process of identifying a highter-level, more generic entity supertype from lower-level entity subtypes.
A single abstract entity object
An entity cluster is formed by combining multiple interrelated entities into ___.
the most important characteristic of an entity is its ___ key, used to uniquely identify each entity instance.
A ___ key is a real-world, generally accepted identifier used to uniquely identify real-world objects.
natural identifier
If one exists, a data modeler used a ___ as the primary key of the entity being modeled.
entity instance or row
The primary key's main function is to uniquely identify a ___ within a table.
Composite primary keys are particularly useful as identifiers of composite entities, where each primary key combination is allowed only once in the ____ relationship.
Unique values
The "____" characteristic of a primary key states the following: The PK must uniquely identify each entity instance. A primary key must be able to guarantee unique values.
The "____" characteristic of a primary key states the following: The selected primary key must not be composed of any attributes that might be considered a security risk or violation.
The "____" characteristic of a primary key states the following: The PK should not have embedded semantic meaning. An attribute with embedded semantic meaning is probably better used as a descriptive characteristic of the entity rather than as an identifier.
Surrogate primary keys are especially helpful when there is no ___ key.
___ keys work with primary keys to properly implement relationships in the relational model.
place a foreign key in one of the entities
The preferred placement for a foreign key when working with a 1:1 relationship is to ___.
one side is mandatory and the other side is optional
When selecting a foreign key placement for a 1:1 relationship, place the PK of the entity on the mandatory side in the entity on the optional side as a FK, and make the FK mandatory when ___.
___ data refer to data whose values change over time and for which you must keep a history of the data changes.
fan trap
a __ occurs when you have one entity in tow 1:M relationships to other entities , thus producing an association among the other entities that is not expressed in that model.
___ relationships occur when there are multiple relationship paths between related entities.
Raw data must be properly ____ formatted for storage, processing and presentation.
Data ___ is a discipline that focuses on proper generation, storage and retrieval of data.
Islands of Information
The term ___ refers to scattered locations storing the same basic data.
data model
A ___ is a relatively simple representation of more complex real-world data structures.
a ___ in a hierarchical model is the equivalent of a record in a file system.
the ___ defines the portion of the database "seen" by the application programs that produce information from the data.
Each row in a relation is called a ___.
Each column in a relationship is called a ___.
relational diagram
a ___ is a representation of the relational database's entities, the attributes within those entities and the relationships between those entities.
crow's foot notion
In ___ a three-pronged symbol represents the "many" side of the relationship.
An ___ is a collection of similar objects with a shared structure and behavior.
In object-oriented terms, a ___ defines an objects behavior.
UML (unified modeling language)
___ is a language based on OO concepts that describes a set of diagrams and symbols used to graphically model a system.
The logical view of the relational database is facilitated by the creation of data relationships based on a logical construct known as a ____.
In a relational table, each column has a specific range of values known as the ___ domain.
In the relational model, ___ are important because they are used to ensure that each row in a table is uniquely identifiable.
a ___ key can be described as a superkey without unnecessary attributes.
The relational operators have the property of closure; that is, the use of relational algebra operators on existing relations (tables) produces new relations.
___ is the real power behind the relational database, allowing the use of independent tables linked by common attributes.
The __ catalog can be described as a detailed system data dictionary that describes all objects within the database.
one to many
The ___ relationship is the relational database norm.
The index key can have multiple attributes, this is called a ___ index.
The ___ refers to a specific table row as an entity instance.
A ___ attribute is an attribute that must have a value.
Primary key
___ are underlined in an ER diagram.
Relationship strength depends on how the primary key of the related entity is formulated, while the relationship ___ depends on how the business rule is written.
The Crow's foot notation depicts the strong relationship with a ___ line between entities.
disjoint subtypes are also known as ___ subtypes.
Subtypes that contain non-unique subsets of the supertype entity set are known as ___ subtypes.
The ____ constraint specifies whether each entity supertype occurrence must also be a member of at least on subtype.
___ completeness means that not every supertype occurrence is a member of a subtype.
primary key
Usually, a data modeler uses a natural identifier as the ____ of the entity being modeled, assuming that the entity has a natural identifier.
Composite keys are useful as identifiers of weak entities, where the entity has a strong ___ relationship with the parent entity.
unique index
If you use a surrogate key, you must ensure that the candidate key of the entity in question performs properly through the use of the ___ and "not null" constraints.
time variant
From a data modeling point of view, ___ data refer to data whose values change over time and for which you must keep a history of the data changes.
fan trap
The most common design trap is known as a ___.
The main concern with redundant relationships is that they remain ___ across the model.