Data Modeling Foundations - Flashcards

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____ is used to reveal the meaning of data.

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Information

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Accurate, relevant, and timely information is the key to ___.

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Good decision making

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End-user data is _____.

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row facts of interest to the end-user

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____ provides a description of the data characteristics and the set of relationships that link the data found within the database.

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Metadata

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The ____ serves as the intermediary between the user and the database.

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DBMS

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A(n) ____ might be written by a programmer or it might be created through a DBMS utility program.

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application program

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The response of the DBMS to a query is the ____.

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query result set

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A(n) ____ database is designed to support a company's day-to-day operations.

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enterprise

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A(n) ___ database is used by an organization and supports many users across many departments.

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workgroup

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A workgroup database is a(n) ___ database.

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multiuser

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Most decision-support data are based on historical data obtained from ___.

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operational databases

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____ data exist in the format in which they were collected.

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unstructured

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____ data exist in a format that does not lend itself to processing that yields information.

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unstructured

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____ data are the result of formatting to facilitate storage, use and generation of information.

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structured

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Most data you encounter is best classified as ____.

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semistructured

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Which of the following is an example of structured data?

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spreadsheet

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XML data is ____.

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semistructured

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A ___ is a logically connected set of one or more fields that describes a person, place or thing.

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record

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A ____ is a collection of related records.

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file

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A(n) ______'s main function is to help you understand the complexities of the real-world environment.

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model

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A(n) ___ represents a particular type of object in the real world.

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entity

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A(n) ___ is anything about which data are to be collected and stored.

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entity

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A(n) ___ is equivalent of a field file system.

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attribute

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A(n) ___ is bidirectional.

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relationship

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A(n) ____ is a restriction placed on the data.

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constraint

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___ are important because they help to ensure data integrity.

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constraints

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___ are normally expressed in the form of rules.

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constraints

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Students and classes have a ___ relationship.

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many to many

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business rules are derived from ___.

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a detailed description of organization operations

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Which of the following is true of business rules?

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serve as a communication tool between the users and designers

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A noun in a business rule translates to a(n) ___ in the data model.

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entity

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A verb associating two nouns in a business rule translates to a(n) ___ in the data model.

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relationship

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The hierarchical data model was developed in the ____.

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1960's

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The object oriented data model was developed in the ____.

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1980's

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VMS/VSAM is an example of a(n) _____.

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file system data model

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Oracle 11g is an example of a(n) _____.

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XML/Hybrid data model

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MySQL is an example of a(n) _____.

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relational data model

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In the ___ model, the basic logical structure is represented as an upside-down tree.

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hierarchical

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In the ___ model, each parent can have many children, but each child has only one parent.

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hierarchical

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The relational data model was developed in the ____.

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1970's

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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.

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network

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A(n) _____ enables a database administrator to define schema components.

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(DDL) data definition language

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The ____ model was developed to allow designers to use a graphical tool to examine structures rather than describing them with text.

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entity relationship

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The ___ model uses the term connectivity to label the relationship types.

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entity relationship

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The ___ data model is said to be a semantic data model.

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object-oriented

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The ___ data model uses the concept of inheritance.

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object-oriented

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One of the limitations of the ____ model is that there is a lack of standards.

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hierarchical

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The ___ model is the end users' view of the data environment.

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external

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A(n) ____ model represents a global view of the database as viewed by the entire organization.

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conceptual

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The relational database model enables you to view data ___ rather than ____.

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logically, physically

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A(n) ____ is perceived as a two-dimensional structure composed of rows and columns.

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table

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Date Attributes contain calendar dates stored in a special format known as the ___ date format.

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Julian

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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.

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determines

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The attribute B is ___ the attribute A if each value in column A determines one and only one value in column B.

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functionally dependent on

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A ___ is any key that uniquely identifies each row.

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superkey

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No data entry at all is known as a ___.

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null

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Controlled ___ makes a relational database work.

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redundancy

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A ___ key is defined as a key that is used strictly for data retrieval purposes.

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secondary

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A ___ key can be described as a superkey without unnecessary attributes, that is, a minimal superkey.

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candidate

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The ___ constraint can be placed on a column to ensure that every row in the table has a value for that column.

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not null

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To be considered minimally relational, the DBMS must support the key relational operators ____, PROJECT and JOIN.

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select

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____, also known as RESTRICT, yields values for all rows found in a table that satisfy a given condition.

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select

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____ yields a vertical subset of a table.

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project

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___ combines all rows from two tables, excluding duplicate rows.

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union

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____ yields only the rows that appear in both tables.

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intersect

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A(n) ____ join links tables by selecting only the rows with common values in their common attribute(s).

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natural

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The equijoin takes its name from the comparison operator ___used in the condition.

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=

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A(n) ____ join only returns matched records from the tables that are being joined.

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inner

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A ___ contains at least all of the attribute names and characteristics for each table in the system.

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data dictionary

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The ___ is actually a system-created database whose tables store the user/designer-created database characteristics and contents.

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system catalog

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In a database context, a(n) ___ indicates the use of different names to describe the same attribute.

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synonym

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The ___relational type is the "relational model ideal."

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1:M

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The ___ relationship should be rare in any relation database design.

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1:1

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Another name for a composite entity is a ___ entity.

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bridge

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A(n) ____ is an ordered arrangement of keys and pointers.

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index

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When you define a table's primary key, the DBMS automatically creates a(n) ___ index on the primary key column(s) you declared.

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unique

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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.)

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logical data independence

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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.

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nonsubversion

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The ERD represents the ___ database as viewed by the end user.

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conceptual

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Some ___ database modeling concepts can be expressed only using the Chen notation.

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conceptual

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Attributes may share a ____.

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domain

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The set of possible values for an attribute is a ___.

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domain

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In an ER diagram, primary keys are indicated by ___.

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underlining

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Ideally, an entity identifier is composed of ___ attributes.

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one

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A ___ identifier is composed of more than one attribute.

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composite

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A ___ attribute can be further subdivided to yield additional attributes.

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composite

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A ___ attribute is one that cannot be subdivided.

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simple

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A ____ attribute can have only one value.

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singlevalued

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____ attributes can have many values.

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multivalued

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Some attributes are classified as _____.

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simple

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Although the conceptual model can handle ____ relationships and multivalued attributes, you should not implement them in the RDBMS.

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M:N

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A ___ should be a derived attribute.

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person's age

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A derived attribute ____.

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need not be stored physically

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A derived attribute is indicated in the Chen model by a ____.

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dashed line

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A relationship is an association between ____.

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entities

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Knowing the ___ number of entity occurrences is very helpful at the application software level.

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maximum & minimum

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In the ERD, cardinality is indicated using the ____ notation.

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(min, max)

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Another word for existence-independent is ____.

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strong

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An entity is said to be ___-dependent if it can exist in the database only when it is associated with another related

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existence

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If an entity can exist apart from one or more related entities, it is said to be ____-independent.

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existence

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When the PK of one entity does not contain the PK of a related entity, the relationship is ____.

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weak

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A ____ entity has a primary key that is partially or totally derived from the parent entity in the relationship.

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weak

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The term ____ is used to label any condition in which one or more optional relationships exist.

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optionality

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The existence of a(n) ____ relationship indicates that the minimum cardinality is at least 1 for the mandatory entity.

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mandatory

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The Crow's foot symbol with two parallel lines indicates ____ cardinality.

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(1, 1)

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A ___ relationship exists when two entities are associated.

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Binary

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A ___ relationship exists when an association is maintained within a single entity.

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Unary

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A ___ relationship exists when three entities are associated.

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Ternary

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____ relationships are most common.

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Binary

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If an employee within an EMPLOYEE entity has a relationship with itself, that relationship is known as a ___ relationship.

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recursive

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A(n) ____ entity is composed of the primary keys of each of the entities to be connected.

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associative

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The associative entity is also known as a ___ entity.

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composite

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The following step occurs first in the process of building an ERD: ____.

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detailed narrative of the organizations description of operations

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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.

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optional

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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 ____.

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weak

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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.

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derived

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Complex ___ requirements may dictate data transformations, and they may expand the number of entities and attributes within the design.

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information

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The extended entity relationship model (EERM) is sometimes referred to as the ___.

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enhanced entity relationship model

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____ is a generic entity type that is related to one or more entity subtypes.

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An entity supertype

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The ___ depicts the arrangement of higher-level entity supertypes (patient entities) and lower-level entity subtypes.

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specialization hierarchy

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Within a specialization hierarchy, every subtype can have ___ supertype to which it is directly related.

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only one

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A specialization hierarchy can have ___ levels of supertype relationships.

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many

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The property of ___ enables an entity subtype to inherit the attributes and relationships of the the supertype.

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inheritance

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One important inheritance characteristic is that all entity subtypes inherit their ___ key attribute from their supertype.

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primary

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at the implementation level, the supertype and its subtypes depicted in the specialization hierarchy maintain a ___ relationship.

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1:1

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A ___ is the attribute in the supertype entity that determines to which entity subtype each supertype occurrence is related.

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subtype discriminator

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The default comparison condition for the subtype discriminator attribute is the ___ comparison.

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equality

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non-overlapping subtypes are subtypes that contain a ___ subset of the supertype entity set.

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unique

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Overlapping subtypes are subtypes that contain ___ subsets of the supertype entity set.

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nonunique

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Partial completeness is symbolized by ___.

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circle over a single line

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is the bottom-up process of identifying a highter-level, more generic entity supertype from lower-level entity subtypes.

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generalization

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An entity cluster is formed by combining multiple interrelated entities into ___.

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A single abstract entity object

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the most important characteristic of an entity is its ___ key, used to uniquely identify each entity instance.

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primary

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A ___ key is a real-world, generally accepted identifier used to uniquely identify real-world objects.

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natural

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If one exists, a data modeler used a ___ as the primary key of the entity being modeled.

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natural identifier

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The primary key's main function is to uniquely identify a ___ within a table.

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entity instance or row

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Composite primary keys are particularly useful as identifiers of composite entities, where each primary key combination is allowed only once in the ____ relationship.

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M:N

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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.

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Unique values

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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.

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security-compliant

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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.

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nonintelligent

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Surrogate primary keys are especially helpful when there is no ___ key.

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natural

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___ keys work with primary keys to properly implement relationships in the relational model.

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Foreign

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The preferred placement for a foreign key when working with a 1:1 relationship is to ___.

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place a foreign key in one of the entities

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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 ___.

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one side is mandatory and the other side is optional

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___ data refer to data whose values change over time and for which you must keep a history of the data changes.

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Time-variant

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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.

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fan trap

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___ relationships occur when there are multiple relationship paths between related entities.

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Redundant

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Raw data must be properly ____ formatted for storage, processing and presentation.

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formatted

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Data ___ is a discipline that focuses on proper generation, storage and retrieval of data.

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management

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The term ___ refers to scattered locations storing the same basic data.

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Islands of Information

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A ___ is a relatively simple representation of more complex real-world data structures.

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data model

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a ___ in a hierarchical model is the equivalent of a record in a file system.

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segment

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the ___ defines the portion of the database "seen" by the application programs that produce information from the data.

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subschema

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Each row in a relation is called a ___.

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tuple

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Each column in a relationship is called a ___.

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attribute

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a ___ is a representation of the relational database's entities, the attributes within those entities and the relationships between those entities.

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relational diagram

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In ___ a three-pronged symbol represents the "many" side of the relationship.

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crow's foot notion

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An ___ is a collection of similar objects with a shared structure and behavior.

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class

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In object-oriented terms, a ___ defines an objects behavior.

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method

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___ is a language based on OO concepts that describes a set of diagrams and symbols used to graphically model a system.

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UML (unified modeling language)

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The logical view of the relational database is facilitated by the creation of data relationships based on a logical construct known as a ____.

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relation

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In a relational table, each column has a specific range of values known as the ___ domain.

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attribute

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In the relational model, ___ are important because they are used to ensure that each row in a table is uniquely identifiable.

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keys

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a ___ key can be described as a superkey without unnecessary attributes.

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candidate

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The relational operators have the property of closure; that is, the use of relational algebra operators on existing relations (tables) produces new relations.

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closure

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___ is the real power behind the relational database, allowing the use of independent tables linked by common attributes.

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join

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The __ catalog can be described as a detailed system data dictionary that describes all objects within the database.

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system

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The ___ relationship is the relational database norm.

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one to many

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The index key can have multiple attributes, this is called a ___ index.

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composite

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The ___ refers to a specific table row as an entity instance.

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ERM

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A ___ attribute is an attribute that must have a value.

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required

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___ are underlined in an ER diagram.

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Primary key

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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.

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participation

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The Crow's foot notation depicts the strong relationship with a ___ line between entities.

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solid

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disjoint subtypes are also known as ___ subtypes.

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nonoverlapping

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Subtypes that contain non-unique subsets of the supertype entity set are known as ___ subtypes.

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Overlapping

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The ____ constraint specifies whether each entity supertype occurrence must also be a member of at least on subtype.

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completeness

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___ completeness means that not every supertype occurrence is a member of a subtype.

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Partial

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Usually, a data modeler uses a natural identifier as the ____ of the entity being modeled, assuming that the entity has a natural identifier.

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primary key

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Composite keys are useful as identifiers of weak entities, where the entity has a strong ___ relationship with the parent entity.

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identifying

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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.

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unique index

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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.

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time variant

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The most common design trap is known as a ___.

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fan trap

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The main concern with redundant relationships is that they remain ___ across the model.

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consistent

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