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Introduction to Databases

Bab 3:

Memodelkan Data


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Desain Database

Tiga bagian proses: Conceptual design: Identifikasi kebutuhan

stakeholder dan persyaratan data,

Logical design:Mengidentifikasi jenis aplikasi

database yang diperlukan; pemodelan data (mengidentifikasi entitas, atribut, hubungan)

Physical design: Implementasi; desain hardwaresecara fisik dan platform; instalasi dan konfigurasiserver dan pembuatan database


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Desain Database


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Jenis Database

Transactional Mendukung transaksi bisnis

contoh, sales, Online TransactionProcessing (OLTP)

Lingkungan client/server sederhana

Concerns : Concurrency, throughput


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Database Types

Decision support system (DSS) Mendukung Keputusan Bisnis

Types: Data warehouses, reporting databases, datamarts

Tujuan Utama:Pemanggilan dan Evaluasi Data

Bulk loading used to add data

Concerns: Access speeds, throughput

Hybrid

Mixture of transactional and DSS types


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Modeling Goals

Design with understanding that:

All applications written for database aredependent on database structure

If database is altered, applications may needto be altered or rewritten

Support business objectives

Simple, easy-to-read, easy-to-

comprehend structure Scalability


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Business Rules

Business rules: Processes and flows used in organizations daily

work, including:

Organizational policies

Calculations and formulas

Rules and regulations

Database systems should supportbusiness rules

Some rules may be better enforced by databasedesign

Others may be better handled through databaseapplication


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Entity-Relationship (E-R) Modeling

Entities: Things to track in database

Physical objects (people or products)

Conceptual entities (loan balances orinterest rates)


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Attributes:

Information tracked about entity

Each entity has attributes

For example: Entity: Employees

Attributes: Hire Date, Pay Rate, Social Security ID,Employee Number, Home Address

One attribute used as unique identifier or

primary key


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Relationships: When one entity references information from

another entity

For example:

Time Card entity must reference an Employeeentity

Time Card entity is referencing entity

Employee entity is referenced entity

Primary keys ensure referential integrity


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Basic Database Objects

Tables: Store unique instances of entity Columns (fields) represent attributes

Rows (records) represent individual occurrences ofthat entity

Views: Customized representations of table information


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Index: Organizes and sorts data

Provides pointer to specific physical location

of data on storage media May be:

Primary or secondary

Clustered or nonclustered

Balanced-tree index (b-tree, or binary treeindex):

Most common type of index in modern databases


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B-Tree Index


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Relationship Types

Three basic types:

Binary relationship:

Relationship between two types of entities

Unary relationship: Relationship with another occurrence

within same entity

Ternary relationship:

Relationship directly involving three entitytypes


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Relationship Types

Cardinality:

Sets maximum number of entities inrelationship

One-to-one

One-to-many

Many-to-many

Modality:

Sets minimum number of entities inrelationship


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Binary Relationships

Simplest type of relationship

Majority of relationships in most relationaldatabases are binary relationships

Entity can have separate binaryrelationships with any number of otherentities in database


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Unary Relationships

Occurrences of an entity type areassociated with other occurrences ofsame entity type

Relate data in a table to itself For example:

Entity (table) Salesperson

One salesperson may act as a backup or

stand-in for another


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Unary Relationships


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Unary Relationships


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Unary Relationships


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Ternary Relationships

Involve three different entities

Can be considered sets of binaryrelationships


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Ternary Relationships


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Many-to-Many Relationships

Help minimize wasted space and optimizeperformance

Intersection data:

Data that is part of many-to-many relationshipand associated with specific, unique instanceof related entities

Associative entities:

Entity designed to associate key values fromtwo entities in many-to-many relationship


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Many-to-Many Relationships


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Associative Entities


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Creating Data Models

To create data model: Identify entities

Identify attributes for each entity

Identify associations between entities

Modeling tools include: Manual (pencil and paper)

Generic draw program (e.g. Visio)

Custom modeling program


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Visio Database Diagrams


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Example: General Hardware Company

Wholesaler and distributor of variousmanufacturers tools and other hardwareproducts

Customers: Hardware and home improvement stores,

which in turn sell products at retail to individualconsumers

Acts as middleman: Buys goods from manufacturers and sells to

retail stores


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Contoh: Good Reading Bookstores

Chain of bookstores

Needs to track data for: Books

Publishers Authors

Customers


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Contoh: Good Reading Bookstores


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Proses Desain Database: Conceptual, logicaldan design

Jenis-jenis database: Transactional, decisionsupport (DSS) dan hybrid

Tujuan Modeling Data: membuat modeldatabase yang strukturnya baik yang sederhana,mudah untuk dibaca dan dipahami serta terukur

Obyek Database: Tabel dan indeks

Tabel: Mendeskripsikan entiti; yang terdiri darikolom (field) dan baris (record), dengan primarykey digunakan sebagai identitas unik dari suaturecord

Ringkasan


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Komponen yang menjadi kunci dari suatuDatabase relasional adalah: Entiti danrelationship

Relationships mungkin berupa binary, unary,

atau ternary, dan memiliki kardinalitas danmodalitas yang berbeda

Relasionship Many-to-many mendukungpersimpangan data dan asosiasi entiti

dalam membuat model data, tahapnya yaitu1. mengidentifikasi entiti,

2. mengidentifikasi atributnya, selanjutnya

3. mengidentifikasi hubungan antar entiti

Ringkasan


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Kata Kunci

Associative entity

Balanced tree index

Base object

Binary relationship

Binary tree index

B-tree index

Bulk loading

Business rules Cardinality

Clustered index

Conceptual design

Concurrency

Database object

Data diagram

Data mart

Data model

Data warehouse Decision support

system (DSS)


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Kata Kunci

Entity-Relationshipdiagram (ERD)

Entity-Relationship(E-R) modeling

Field

Hybrid database

Identifier

Index

Intersection data

Large object (LOB)data

Leaf node

Logical design

Many-to-many (M-M)binary relationship

Modality

Node

Nonclustered index

Object-relation model(ORM)

One-to-many (1-M)binary relationship


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Kata Kunci

One-to-one (1-1)binary relationship

Online transactionprocessing (OLTP)

Physical design

Primary index

Primary key Record

Referenced entity

Referencing entity

Referential integrity

Reporting database

Scalable

Secondary index

Stakeholder

Ternary relationship

Transactionaldatabase

Throughput

Unary relationship


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