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Not merely a collection of files

Central source of data

Database

DBMSC-M-U;retrieval; and generation of reports

DBA

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Effectiveness Objectives:

1. Ensuring that data can be shared among users2. Maintaining data that are both accurate and

consistent

3. Ensuring that all data required for future

applications will be readily available

4. Allowing the database to evolve as the needs ofthe users grow

5. Allowing users to construct their personal view of

the data without concern for the way the data arephysically stored

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1. Reality, Data Metadata

Reality

Data

Metadata

Entities

Data ItemDefinitions

Data Item

Occurences

Record

Occurrences

RecordDefinitions

Attributes

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Any object or event about which someone collects data

A person, place or thing, an event or unit of time

Entity Subtypeadditional minor entity

Symbolized as a smaller rectangle within the entity rectangle

A special one-to-one relationship

Eliminate situation in which an entity may have null fieldsstored on database

StudentInternship

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Associations between entities

AKA data associations

Types of relationships:

One-to-one relationship (1:1)

One-to-many or Many-to-one relationship (1:M)

Many-to-many relationship (M:M)

Self-join relationshiprelationship connecting it toitself

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ProductProductPackage

Employee Office

has

is assignedto

Physician Patient

Employee Department

treats

belongs to

Product Product

Product Product

One-to-One(1:1)

One-to-Many (1:M) orMany-to-One (M:1)

Many-to-Many(M:N)

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Entity

Associative Entity

Attributive Entity

To 1 relationship

To many relationship

To 0 or 1 relationship

To 0 or morerelationship

To more than 1relationship

A class of persons,places, or things

Used to join two entities

Used for repeating groups

Exactly one

One or more

Only zero or one

Can be zero, one, or more

Greater than one

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Physician(Physician-Name,

Physician-Address,Physician-Phone,Specialty)

Patient

treatsis taken care of

by

(Patient-Name,

Patient-Address,Patient-Phone,Date-First-Visit)

InsuranceCarrier

Treatmentexperiences

is given to

(Product-Name,

Patient-Name,

Description,Date,Symptom)

(Carrier-Name,

Carrier-Address,Plan-Description) Prescription

(Product-Name,

Dosage,

Manufacturer,Amount)

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Some characteristic of an entity Data element (data dictionary)data items

attribute

Data itemssmallest units in a file or database

AKA fieldrepresents something physical not logical

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Entity

Salesperson Salesperson NumberSalesperson NameCompany Name

Address

Sales

87254KaytellMusic Unlimited45 Arpeum Circle

P20,765

Package WidthHeightLengthWeightMailing AddressReturn Address

216163765 Dulcinea DriveP.O. Box 341, Spring Valley, MN

Order Product(s)Description(s)Quantity OrderedLast Name of CustomerFirst InitialStreet Address

CityStateZip CodeCredit Card NumberDate Order Was Placed

AmountStatus

B521My Fair Lady compact disc1KileyR.765 Dulcinea Drive

La ManchaCA934076587988701/03/2010$6.99Backordered

Data Item Value

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