Server Design

Arcs and Sub Entities

ER Diagram

Transformation Options for Exclusivity

TITLE

MOVIE

GAME

• Supertype• Explicit

subtypes• Implicit

subtypes• Arcs

Supertype and Supertype and subtypessubtypes

The Supertype Option

TITLE# PRODUCT CODE* TITLE

MOVIE* CATEGORY

. . . o AUDIO

GAME* CATEGORY

. . . o MINIMUM MEMORY

Supertype

TITLES# * PRODUCT_CODE

* TI_TYPE * TITLE

. . . o CATEGORY o AUDIO o CATEGORY_CATEGORY o MINIMUM_MEMORY

Supertype Option

Result of Supertype Option

Discriminator Column

The Explicit Subtype Option

TITLE# PRODUCT CODE* TITLE

ExplicitSubtype

GAMES# * PRODUCT_CODE * TITLE * CATEGORY o MINIMUM_MEMORY . . .

MOVIES# * PRODUCT_CODE * TITLE * CATEGORY o AUDIO . . .

GAME* CATEGORY

. . . o MINIMUM MEMORY

MOVIE* CATEGORY

. . . o AUDIO

Implementing Explicit Subtypes

• Select the In Set check box for the subtypes only

Table Mappings

TITLE No MappingIncludedIncluded

--GAME--MOVIE

In Set

MOVIES

GAMES

The Implicit Subtype Option

(rare and not recommended)

TITLE# PRODUCT CODE* TITLE

GAME* CATEGORY

. . . o MINIMUM MEMORY

ImplicitSubtype

TITLES# * PRODUCT_CODE * TITLE

MOVIES# * PRODUCT_CODE * TITLE * CATEGORY o AUDIO . . .

GAMES# * PRODUCT_CODE

* TITLE * CATEGORY o MINIMUM_MEMORY . . .

MOVIE* CATEGORY

. . . o AUDIO

Implementing Implicit Subtypes

Table Mappings

TITLE No MappingIncludedIncluded

--GAME--MOVIE

In Set

TITLES

GAMES

MOVIES

• Select the In Set check box for the supertype and the subtypes

The Ordinary Arc

The Result

The Arc Option(rarely applicable)

TITLE# PRODUCT CODE

* TITLE

MOVIE* CATEGORY

. . . o AUDIO

GAME* CATEGORY

. . . o MINIMUM MEMORY

Arc

TITLES# * PRODUCT_CODE

* TITLE

. . . o MO_MO_ID o GA_GA_ID

. . .

GAMES# * GA_ID

* CATEGORY

. . . o MINIMUM_MEMORY

MOVIES# * MO_ID

* CATEGORY

. . . o AUDIO

Table Mappings

TITLEIncludedIncluded

--GAME--MOVIE

In SetNo Mapping

Implementing Arcs—First Run

• Choose tables only

Run OptionsTypes of elements that you want to create

Tables Columns Keys

• Include supertypes and subtypes

Implementing Arcs—Second Run• Map the arc

Table Mappings

TITLE Mapped--GAME--MOVIE

ArcArc

Arc TableTITLES

MOVIESGAMES

EntityIn Set

• Select tables, columns, and keysRun Options

Types of elements that you want to createTables Columns Keys

Choosing Implementation

Criterion Split Combine

Common Attributes? Few Many

Common Relations? Few Many

Common use? No Yes