E-R Diagram

Bagian IIb

Relationship Terminologi

Database Desain

Conceptual

perspective

User’s perspective

Database

Requirements

Logical

Schema

(Relational)

Conceptual

Design

The Entity

Relationalship (ER)

Model is one of the

most widely used

mthod for

conceptual design

Logical

Design

(Mapping)

Conceptual

Schema

(ER)

The Relational Model

is the basic for

several commercial

DBMSs

Internal

Schema

Phases of Database Design

• First step of the design process is to identify the “Universe of Discourse” (UoD)

• The database to be built will not model everything in the world, but rather some “mini-world” or “Universe of Discourse”.

• The UoD is the relevant portion of the real world to be modeled by the database

3

Universe

of Discourse

Phases of Database Design

• Functional Analysis consists of specifying operations (retrievals, updates) that will be applied to the database

• Various techniques for software design exist, such as sequence diagrams, flowcharts, DFDs, etc.

• Refer to Software Engineering Texts

4

Universe

of Discourse

REQUIREMENTS

COLLECTION

AND ANALYSIS

FUNCTIONAL

ANALYSIS

APPLICATION

PROGRAM

DESIGN

..

.

Phases of Database Design

• Description of the data requirements of users

• Expressed using a high level model such as ENTITY-RELATIONSHIP (ER)

• A database schema in the ER Model can be represented pictorially (ER diagrams)

• ER Model contains detailed descriptions of:

What are the entities and relationships in the enterprise?

What information about these entities and relationships should we store in the database?

What are the integrity constraints or business rules that hold?

5

Universe

of Discourse

REQUIREMENTS

COLLECTION

AND ANALYSIS

FUNCTIONAL

ANALYSIS

APPLICATION

PROGRAM

DESIGN

..

.

CONCEPTUAL

DESIGN

Phases of Database Design

• Actual implementation of the database, using a commercial DBMS

• Depends on the logical/implementation model of the DBMS, for example Relational Database Model, Object Oriented Database Model.

• Conceptual Model (ER) is mapped to the implementation model (Relational) in this phase

6

Universe

of Discourse

REQUIREMENTS

COLLECTION

AND ANALYSIS

FUNCTIONAL

ANALYSIS

APPLICATION

PROGRAM

DESIGN

..

.

CONCEPTUAL

DESIGN

LOGICAL

DESIGN

Phases of Database Design

• Database is tuned for storage and performance

• Includes specification of storage structures, access paths, file organization etc.

7

Universe

of Discourse

REQUIREMENTS

COLLECTION

AND ANALYSIS

FUNCTIONAL

ANALYSIS

APPLICATION

PROGRAM

DESIGN

..

.

CONCEPTUAL

DESIGN

LOGICAL

DESIGN

PHYSICAL

DESIGN

Phases of Database Design

• Data Structures and Operations are closely linked

• Design of the two is done in parallel and subsequent implementation in interdependent

8

Universe

of Discourse

REQUIREMENTS

COLLECTION

AND ANALYSIS

FUNCTIONAL

ANALYSIS

APPLICATION

PROGRAM

DESIGN

..

.

CONCEPTUAL

DESIGN

LOGICAL

DESIGN

PHYSICAL

DESIGN

Conceptual Design

9

Universe

of Discourse

REQUIREMENTS

COLLECTION

AND ANALYSIS

FUNCTIONAL

ANALYSIS

APPLICATION

PROGRAM

DESIGN

..

.

CONCEPTUAL

DESIGN

LOGICAL

DESIGN

PHYSICAL

DESIGN

CONCEPTUAL

DESIGN

Database

Requirements

Conceptual Schema

(High Level Data Model,

e.g. ER, NIAM, SDM)

Defines the UoD,

and captures

semantics &

constraints of the

UoD

Serves as a

medium for

communicating

the UoD

Focus of

this lecture

Relationship DefinitionRelationship pada E-R diagram adalah hubungan asosiasi antaradua atau lebih entity type

Hubungan ini terjadi karena :

1. Secara konsep E-R diagram memang ditujukan untuk dapatmemperlihatkan hubungan makna antar entity yang dibentuk

2. Secara alamiah wujud-wujud di dunia nyata memilikiketerhubungan satu dengan yang lainnya

Ch :

- Seseorang memiliki kendaraan, maka dapat diidentifikasibahwa ada hubungan kepemilikan yang dapat menunjukkansiapa memiliki kendaraan yang mana

- Sebuah toko menjual beberapa barang dagangan, dapatdinyatakan adanya hubungan yang menjelaskan toko yang mana menjual barang apa saja

10

Membangun Relationship

Gagasan utamanya adalah ingin membangun suatuinformasi yang terkait dengan makna-makna dariketerhubungan antar entity.

Ch :

-Ingin diketahui, pada semester ini siapa sajamahasiswa yang mengambil matakuliah basdat

-Ingin diketahui, siapa saja yang menggunakanruangan kuliah SB-403

11

Relationship Types and Sets

• A Relationship Type defines the relationship, and a Relationship Set represents a set of relationship instances

• A Relationship Type thus defines the structure of the Relationship Set

Relationship Type and corresponding Set are customarily referred to by the same name

12

Formally ...

Relationship Type R didefinisikan sebagai sebuah set asosiasi antara n buah entity types E1, E2, ... En, R adalah subset dari produk Cartesius E1 x E2 x En ...

Setiap Ei dikatakan "berpartisipasi" dalam relationship type

Sebuah Relationship Set R adalah himpunan dari relationship instances ri, dimana setiap ri berasosiasi dengan n individual entities (E1, E2, ... En)

Setiap Ei dikatakan "berpartisipasi" dalam relationship instance

13

Product

Keeps

Store

descrip

qty

price

pname

manager

Locations

sname

Entity Type

Relationship Type

Relationship Type

Product

Keeps

Store

pname

sname

pname

sname

Relationship Set ( n kombinasi )Keeps { sname,pname }

Relationship

Instance( 1 kombinasi )

Relationship Set

• Keeps (table) set of relationship

Contoh

sname pname

Borma Pepsodent

Borma Sabun lux

Borma Susu dencow

Borma Supermie

Griya Sabun cuci

Griya Pepsodent

Alfa mart Susu dencow

… …

instance