Informatiesystemen in de Bouw7M711

Joran Jessurun en Jos van Leeuwen

Week 3

Database

• A database is a collection of data.

• Databases can be stored in one or more files, or can be managed by a software system called Database Management System (DBMS)

What makes a database

• Add Data

• Delete Data

• Change Data

• Lookup or search for data

• Organize Data

Key Terminology

• Table• Column• Record• Field

• Primary Key• Foreign Key

Types of databases

• Flat databases

• Index databases

• DBMS based databases

DBMS Services

• Schemas• Consistency checks• Guarantee of no data corruption after crash• Concurrent access for multiple readers and

writers.• Backup and recovery• Authentication and access control• Support for Structured Query Language (SQL)

DBMS Flavors

• From relational

• To object oriented

DBMS Systems

• Oracle

• Sybase

• Microsoft SQL Server

• MySQL

Paradox

• Indexed Database

• Every table is contained in a *.DB file

• The primary key is indexed in a *.PX file

• Accessed trough the Borland Database Engine

Borland Database Engine

• Database independent

• Adds services for flat and indexed database access

• Used by Delphi

• Makes use of Aliases

• Like Microsoft’s ADO components

UML Profile for Database Design

• Rational Software Corporation

• For designing databases

• Uses tagged parameters and stereotypes

• Only a subset will be explained

Database Diagram Elements

• Table

• Column

• Primary key

• Foreign key

• Identifying relationship

• Non-identifying relationship

Database Diagram Elements (2)

Table (stereotype <<table>>)

Not used

Not used

Primary key (stereotype <<pk>>)

Foreign key (stereotype <<fk>>)

Primary/Foreign key (stereotype <<pk/fk>>)

Non-identifying relationship

Identifying relationship

Example 1

Mapping Logical Design To Database Design

• Synchronization• Classes > Tables• Attributes > Columns• Associations > Relations• Normalization• There are more ways to

do it

Mapping Classes To Tables

• Map persisted classes to tables• Many to many associations must be broken down

to one to many associations using an association table.

«pk» +Class1ID

«table»Class1

«pk» +Class2ID

«table»Class2

«pk/fk» +Class1ID«pk/fk» +Class2ID

«table»Association Class

1

*

1

*

Mapping Subtype Classes to Tables

• One table per class

• One table per concrete class

• One table per hierarchy

Mapping Attributes to Columns

• Map persistent attributes• Don’t map calculated attributes• Can use Generic Types first, later use

database specific types.

Generic Types: Boolean, Currency, Date, Double, Integer, Long, Single, String

Example 2

Database Desktop

• Create and fill tables

• Execute database queries

• Build on BDE

Database Desktop Example

«pk» +ISBN+Title+Description

«table»Book

«pk» +BookID«fk» +ISBN+Count

«table»LibraryBook

«pk» +ClientID+Name+Adres

«table»Client

«pk/fk» +ClientID«pk/fk» +BookID+Lend+Days

«table»BookClient

1

*

1 *

1 *