ISM3212 Midterm study guide

In the entity relationship diagram (ERD), cardinality is indicated using the _____ notation, where max is the maximum number of associated entities and min represents the minimum number of associated entities.

(min,max)

The hierarchical data model was developed in the _____

1960's

The relational data model was developed in the _____

1970's

The object-oriented data model was developed in the _____

1980's

A(n) _____ is the equivalent of a field in a file system

Attribute

To simplify the conceptual design, most higher-order relationships are decomposed into appropriate equivalent _____ relationships whenever possible.

Binary

Another name for a composite entity is a(n) _____ entity

Bridge

A _____ key can be described as a minimal superkey, a superkey without any unnecessary attributes

Candidate

_____ expresses the minimum and maximum number of entity occurrences associated with one occurrence of the related entity.

Cardinality

Which of the following types of HDFS nodes acts as the interface between the user application and the HDFS?

Client node

The purpose of an entity _____ is to simplify an entity-relationship diagram (ERD) and thus enhance its readability.

Cluster

The database structure in a DBMS is stored as a _____

Collection of files

Each table _____ represents an attribute

Column

A _____ attribute can be further subdivided to yield additional attributes

Composite

The entity relationship diagram (ERD) represents the _____ database as viewed by the end user

Condensed

A(n) _____ is a restriction placed on the data

Constraint

_____ are normally expressed in the form of rules

Constraints

A(n) _______ enables a database administrator to describe schema components

Data definition language(DDL)

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

Data definition language(DLL)

_____ exists when different versions of the same data appear in different places

Data inconsistency

The term _____ refers to an organization of components that define and regulate the collection, storage, management and use of data within a database environment

Database System

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

Enterprise

A relationship is an association between _____.

Entities

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

Entity

Knowing the minimum and maximum number of _____ occurrences is very helpful at the application software level.

Entity

The CUSTOMER table's primary key is CUS_CODE. The CUSTOMER primary key column has no null entries, and all entries are unique. This is an example of _____ integrity

Entity

The _____ model uses the term connectivity to label the relationship types

Entity relationship

A subtype contains attributes that are common to all of its supertypes.

False

A weak relationship exists if the primary key of the related entity contains at least one primary key component of the parent entity

False

An implementation-ready data model needn't necessarily contain enforceable rules to guarantee the integrity of the data

False

Corporations use only structured data

False

Data and information are essentially the same thing

False

Data anomaly is defined as the condition in which all of the data in the database are consistent with the real-world events and conditions

False

Field refers to a collection of related records

False

In a natural join, the column on which the join was made occurs twice in the new table

False

In specialization hierarchies with multiple levels of supertype and subtypes, a lower- level subtype can inherit only a few of the attributes and relationships from its upper- level supertypes.

False

The existence of a mandatory relationship indicates that the minimum cardinality is 0 or 1 for the mandatory entity

False

The relational model is hardware-dependent and software-independent

False

A _____ is a character or group of characters that has a specific meaning

Field

Accurate, relevant, and timely information is the key to ____

Good decision making

In organizations that generate large number of transactions, _____ are often a top priority in database design

High processing speeds

In a database context, the word _____ indicates the use of the same attribute name to label different attributes

Homonym

_____ is the result of revealing the meaning of raw facts

Information

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

Inheritance

A(n) _____ only returns matched records from the tables that are being joined

Inner join

Referential dictates that the foreign key must contain values that match the primary key in the related table, or must contain null

Integrity

Date attributes contain calendar dates stored in a special format known as the _____ date format

Julian

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

Keys

According to Codd's _____ rule of relational databases, application programs and 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)

Logical data independence

The conceptual model can handle _____ relationships and multivalued attributes.

M:N

A specialization hierarchy can have _____ level(s) of supertype/subtype relationships.

Many

_____ provide a description of the data characteristics and the set of relationships that link the data found within the database

Metadata

Which of the following types of HDFS nodes stores all the metadata about a file system?

Name node

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

Natural

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

Natural identifier

The "_____" characteristic of a primary key states that the primary key should not have embedded semantic meaning.

Nonintelligent

According to Codd's _____ rule of relational databases, if the system supports low-level access to the data, users must not be allowed to bypass the integrity rules of the database

Nonsubversion

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

Nonunique

In the context of total completeness, in a(n) _____, every supertype occurrence is a member of at least one subtype.

Overlapping constraint

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

Primary

The response of the DBMS to a query is the ___________

Query result set

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

Recursive

MySQL is an example of the _____

Relational data model

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

Relationship

A(n) _____ is bidirectional

Relationship

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

SELECT

Most data that can be encountered are best classified as _____

Semistructured

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

Single abstract entity object

If an entity can exist apart from all of its related entities, then it is existence-independent, and it is referred to as a(n) _____ entity

Strong

Which of the following is a specialization hierarchy disjoint constraint scenario in case of partial completeness?

Subtype discriminator can be null

A(n) _____ is any key that uniquely identifies each row

Superkey

Which of the following is a specialization hierarchy overlapping constraint scenario in case of partial completeness?

Supertype has optional subtypes

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

System catalog

Data is said to be verifiable if

The data always yields consistent results

Which of the following is true of spreadsheet applications?

They enhance the users ability to understand the data

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

True

An implementation-ready data model should contain a description of the data structure that will store the end-user data

True

Each row in the relational table is known as an entity instance or entity occurrence in the ER model

True

Entity supertypes and subtypes are organized in a specialization hierarchy.

True

One disadvantage of a database system over previous data management approaches is increased costs

True

Relational algebra defines the theoretical way of manipulating table contents using relational operators

True

Specialization is the top-down process of identifying lower-level, more specific entity subtypes from a higher-level entity supertype.

True

The DIVIDE operation uses one single-column table (e.g., column "a") as the divisor and one two-column table (e.g., columns "a" and "b") as the dividend.

True

The relationships depicted within the specialization hierarchy are sometimes described in terms of "is-a" relationships.

True

Within the database environment, a data model represents data structures with the purpose of supporting a specific problem domain

True

You can think of a table as a persistent representation of a logical relation

True

A data dictionary is sometimes described as "the database designer's database" because it records the design decisions about tables and their structures

Ture

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

Unary

Nonoverlapping subtypes are subtypes that contain a(n) _____ subset of the supertype entity set.

Unique

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

Unique

The "_____" characteristic of a primary key states that the primary key must uniquely identify each entity instance, must be able to guarantee unique values, and must not contain nulls.

Unique value

_____ data exist in the format in which they were collected

Unstructured

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

Weak

A(n) _____ database supports a relatively small number of users (usually fewer than 50) or a specific department within an organization

Workgroup

The first step in building an entity-relationship diagram (ERD) is _____.

identifying the business rules based on the description of operations

Ideally, an entity identifier is composed of _____ attribute(s)

one