Ch 8

If there are not attributes that can have more than one value for a single intance of the entity; and if any attributes that can have multiple values actually descirbe a separate entity, possible an entity and a relationship is true for :

A) 1NF

An entity that inherits its primary key from more than one entity is called a(n): A) associative entity B) concatenated entity C) ternary D) many-to-many cardinality E) none of these

A) Associative Entity

A key value whose structure communicates data about an entity:

A) Is known as intelligent key

An entity whose instances store attributes that are common to one or more entities are :

A) Super-types

______ codes use finite combination of letters or numbers to describe entity instance

Alphabetic

Finite combinations Letter or numbers

Alphanumeric

Piece of Data about instance of a given entity

Attribute

Which of the following is NOT a guideline fro creating a business coding scheme?

B) The full code must result in redundant values for entities

An entity is in third normal form if :

B) Values of a non-primary key attributes are not dependent on any other non-primary key attributes

2 Entities 3

Binary Ternary

The number of entities that can participate in a relationship is known as :

C) the degree of the relaionship

Differentiate between candidate keys, primary keys, and alternate keys. Can each of these be a concatenated key?

Candidate Key : candidate to become the primary identifier Primary Key: candidate key that is used to uniquely identify a single entity instance Alternative Keys a candidate not selected to become the primary key

Minimum and Maximum - Occurrences

Cardinality

Difference between cardinality and Degree?

Cardinality: shows the complexity of each relationship Degree : number of entities that participate in the relationship

Entities and Relationships

Context Data model

What defines the minimum and maximum number of occurrences of one entity that may be related to single occurrence of the other entity?

D. Cardinality

Differentiate between data modeling and data analysis

Data analysis (normalization) is a process that prepares data model for implementation as simple, non redundant, flexible, and adaptable database

Other Data Modeling name

Database modeling

Value when user does not specify one

Default Value

Number of entities in relationship

Degree

Attributes Calculated

Derived Attributes

Define Value Legitimately take

Domain

The three properties of a attribute

Domain Data type Default

A true entity:

E) All of the above

A(n) _______ is something that the business needs to store data

Entity

Difference between entities and entity instances. Why don't we try to model instances ?

Entity is a class of person, place, object, event, or concepts about which we need to capture and store data. Entity instance is a single occurrence of an entity Each occurrence of an entity is described by similar pieces of data

A foreign key in the parent entity always matches the primary key in the child entity T or F

F

Generalization is a tehcnique wherein the domains common to several types of attributes are grouped into their own entity, called a subtype T or F

F

The domain value for an attribute is the vule that will be recorded if no specified by the user T or F

F

The value of a key can be null. T or F

F

A data-to-location CRUD matrix is a table in which garbage values that fall outside the main of an attribute are identified and used for data verification T or F

False

Data analysis is a process that prepares a logical model for implementation as a redundant, explicit, and finite database through a technique called generalization T or F

False

A recursive relationship is a relationship with a degree of infinity, becuase there is no limit to how many entities participate in the relatinship T or F

False A recursive relationship is a relationship with a degree of one (1), only one entity participates in the relationship.

In a good data mode, each data attribute describes at most one place

False Each attribute, other than foreign keys, describes at most one entity

A many-to-many relationship is one in which many entities are associates with other attributes of a different entity

False M : M relationship is one which many instances of one entity are associated with many instances of another entity.

If use-case narratives have been written during the requirements analysis phase, analysts can scan them for verbs to discover data attributes and entities

False Scan each use-case narrative for nouns

A data-to-location CRUD matrix is a table in which garbage values that fall outside the domain of an attribute are identified and used for data verification T or F

False A data-to location CRUD matrix is a table in which the rows indicate entities (and possible attributes); the columns indicate locations; and the cells (the interseption of the row and columns) document level of access where C= Create; R=read; U=update; and D=delete or deactivate

Another name for the logical data model is the database schema

False Another name for the physical data model is the database schema

Once the data model has been defined, it is trivial to identify the remaining data attributes T or F

False It is not trivial task to identify the remaining data attributes. To Accomplish this task, it is necessary to have a thorough understanding of the data attributes for the system

Approach discover and exploit commonalities between entities Attributes are grouped - supertypes and subtypes

Generalization

_______ codes provide a top-down interpretation for an entity instance.

Hierarchical

Top-down Interpretation

Hierarchical Codes

Every Entity must have

Identifier or key

What is an associative entity? What role does it play in tenary relationships? What role does it play in resolving nonspecific relationships?

Inherits its PK from more than one other Entity Connect ternary relationship Resolves nonspecific or M:M.Using the FK from other entities

What is subsetting criteria?

Is an attribute whose finete values divide all entity instance into useful subsets

A(n)_________ relationship is where many instances of one entity are associated with many instance of another entity

Many to many or nonspecific

_______relationship are those in which each of the participating entities has its own independent primary key

Non identifying

Categories of Entities

Person Places Object Events Concepts

Candidate Key is a candidate of

Primary Key or identifier

Relationship different instances same entity

Recursive or Unary

Natural association one or many

Relationship

Alternative Key

Secondary Key

Sequentially generated numbers Codes

Serial Codes

In ________________________ codes , each digit or group of digits describes a measurable or identifiable characteristic of the entity instance.

Significant Position

Attribute finite values divide all instances into useful subsets

Subsetting criteria or Inversion Entry

What is a weak entity?

The child entity of any identifying relationship is frequently referred to as a "weak" entity because its identification is dependent on the existence of the parent entity's existence

How does a data-location-CRUD matrix supplement a data model

The data-location-CRUD matrix can supplement the data model by identifying what data and access rights are needed at which locations

Alphabetic Codes use finite combination of letters (and possibly numbers) to describe entity instances

True

An Alternate key is alknow as a secondary key

True

An enterprise data model typically identifies only the most fundamental of entities of the enterprise.

True

Some experts suggest that you avoid the use of intelligent keys when designing your data model. They argue that because characteristics can change it violates the rules that value of a key should not change over the lifetime of each entity instance

True

The Data model for a single information system is usually called an application data model

True

The requirements analysis results in a logical data model that is develop in stages as follows: 1) Context Data Model (Entities and Relationship) 2)Key-based data model 3)Fully attributed data model 4)Normalized data model

True

All relationship are

bi-directional

A group of attributes that uniquely identifies an instance of an entity is called a(n) __________________________________.

concatenated key

_____ is a diagrammatic technique used to document the shape of a business or information system in terms of its business locations

data to location CRUD Matrix

______ attributes are those whose values can either be calculated from other attibutes or derived through logic from the values of other attributes

(Derived )

____ is a data analysis technique that organizes data attributes such that they are grouped to form non-redundant, stable, flexible, and adaptive entities.

(Normalization)

Inherits PK from 1 or more entities. Connecting Entities

Associative Entity

Numbers divided into groups based on Business meaning

Block

When a non-key attribute is dependent on another non-key attribute (other than by derivation) is known as:

C) a transitive dependency

group of attributes uniquely identificate

Concatenated Key

Organizing and Documenting a system's data

Data modeling

PK one entity contribute Identify another Relationship

Foreign

M to M

Non specific Relationship

Each participant has its own PK

Non-Identifying

Process Simple Nonredundant Flexible Adaptable database

Normalization

Each digit or group describes a measurable or identifiable characteristics

Significant position

In_____ codes, each digit or group of digits describes a measurable or identifiable characteristic of the entity instance.

Significant position

The context data model is prepared during the problem analysis phase and only includes entities and relationship, but attibutes

True