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Database Systems Fundamentals

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Title: Database Systems Fundamentals


1
Database SystemsFundamentals
Data Information
Abstract Machine
Database, DBMS Data Model
Fundamentals
Database Systems E-Business
Data Management Layer
2
Database Systems as Abstract Machines
Intension
Extension
FactBases
Universe of Discourse
Database
Distribution
Multi-User Access
Integrity
Formalisms
Functions
Constraints
Update
Transactions
Query
State
3
Universe of Discourse
Database Design
Universe of Discourse
Database Schema
Database Design
Teaching Domain
Teaching Database
4
Persistence
Data in a database persists over and above any
particular use of such data
Student Program
Non-persistent Data
Student Data
Student Program
5
Intension/Extension
Schema university Classes Modules Students Re
lationships Students take Modules Attributes M
odules have names Students have names
Database Design
Teaching Domain
Extension university Modules Relational
Database Systems Relational Database
Design Students John Davies Peter Jones Susan
Smith Takes John Davies takes Relational
Database Systems
6
States, Transactions and Constraints
students can only take currently offered modules
State
State
Extension university Modules Relational
Database Systems Relational Database
Design Students John Davies Peter Jones Susan
Smith Takes John Davies takes Relational
Database Systems John Davies takes Relational
Database Design
Extension university Modules Relational
Database Systems Relational Database
Design Students John Davies Peter Jones Susan
Smith Takes John Davies takes Relational
Database Systems
Enrol John Davies in Relationals Database Design
7
Distributing Data
Coordinator System
Database Fragment
Database Fragment
Database Fragment
One application data model/many data
fragments/replicates
8
Conceptual Modelling
Conceptual Modelling
Universe of Discourse
Conceptual Model/ Schema
Schema university Classes Modules Students Re
lationships Students take Modules Attributes M
odules have names Students have names
Database Design
Teaching Domain
9
Summary - Abstract Machine
  • A database is a model of some universe of
    discourse (UOD).
  • A database consists of two parts an intensional
    part and an extensional part.
  • The intensional part (schema) of a database
    defines the structure of the extensional part.
  • The process of developing the schema for some
    database is database design.
  • The extensional part of a database consists of a
    collection of positive assertions.
  • Integrity is the problem of ensuring that a
    database remains an accurate reflection of its
    UOD.
  • Integrity is ensured through the application of
    integrity constraints.
  • There are two types of integrity constraint
    static and transition constraints.
  • A static constraint is a restriction defined on
    a database state.
  • A transition constraint is a rule that relates
    given states of a database.
  • To perform useful activity with a database two
    types of function are needed update and query
    functions.
  • Update functions cause changes to the state of a
    database.
  • Query functions are mainly used to check whether
    a fact or group of facts holds in a given
    database state.
  • To implement the elements of a database system
    we need some formalism (data model).
  • Data normally needs to be shared between
    numerous different users. A database system
    therefore needs to provide concurrency. Sharing
    data for different uses requires the concept of a
    view.
  • Data is frequently distributed within a database
    system.

10
DataInformation
Sign
Vocabulary
Data
Information
Grammar
Semantics
Intension
Syntactics
Pragmatics
Syntax
Empirics
Semiotics
Designation
Extension
Web
Data Model
Data Format
Data Structure
Data Element
Data Item
11
Signs
Signification
Human
Information
Data
Sign System
12
Levels of Signs
Semiotics
Pragmatics
Context
Semantics
Meaning
Syntactics
Structure
Empirics
Medium
13
Semantics
Sign
Data
Information
Intension
Designation
Extension
14
Syntactics
Language
Vocabulary
Formal Language
Grammar
Natural Language
Syntax
15
Schemas
Formal Language
Universe of Discourse
Database Schema
16
Data Formats
Data Structure
Data Element
Data Element
Data Item
Data Item
Data Item
Data Item
17
Data Types
Data Type
Data Item
Data Item
Data Item
Data Item
18
Summary Data and Information
  •  A database can be considered as an organised
    collection of data which is meant to represent
    some Universe of discourse.
  •  Data are facts. A datum, a unit of data, is one
    symbol or a collection of symbols that is used to
    represent something.
  •  Data by itself is meaningless. To prove useful
    data must be interpreted. Information is
    interpreted data. Information is data placed
    within a meaningful context. Information is data
    with an assigned semantics or meaning.
  •   The distinction between data and information
    is embodied in the concept of a sign.
  •   Semiotics or semiology is the study of signs
    or more precisely of sign-systems.
  •  Signs and sign-systems can be considered in
    terms of four inter-dependent levels pragmatics,
    semantics, syntactics and empirics.
  •  The term universe of discourse (UoD) or domain
    of discourse is sometimes used to describe a
    context within which a group of signs (usually
    linguistic terms) is used continually by a social
    group or groups. For work in the area of
    information systems it is important to develop a
    detailed understanding of the structure of these
    terms. In database work this structure is known
    as a schema. A schema is an attempt to develop an
    abstract description of some UoD usually in terms
    of a formal language.
  •  To build a schema we must have a system of
    signs or a language we can use. Such a language
    must have an agreed vocabulary, grammar and
    syntax. The formal language used for defining
    schemas is generally described as a data model.
  •   In general terms, the syntax of data
    definition in any data model tends to use a
    hierarchy of data items, data elements and data
    structures.

19
Database, DBMSData Model
Data Model
Data Manipulation
Data Maintenance
Data Integrity
Database System
Requirements Elicitation
Data Definition
Conceptual Modelling
Data Retrieval
Data Control
DBMS
Database Development
Logical Modelling
Database
Physical Modelling
Data Sharing
Data Independence
Data Integration
Data Security
Data Abstraction
Data Integrity
20
Piecemeal Development
Student Data
Student Information System
Staff Data
Staff Information System
Module Data
Modules Information System
21
Properties of a Database System
Data Sharing
Data Integration
Data Integrity
Data Security
Data Abstraction
Data Independence
22
Database Management System
ICT System
Data Management Subsystem
DBMS
Data Retrieval
Data Maintenance
Data Control
Data Definition
Database
23
Data Models
Architecture
Blueprint
Primitive
Classic
Semantic
24
Database System
Database System
Data Model
Database
DBMS
25
History of Data Management
4000BC
1900
1980
1995
1955
1965
1999
Manual Record Managers
Multi-Media Databases
Punched-Card Record Managers
On-Line Network Data Managers
Web-Based Database Systems
Programmed Record Managers
Relational Data Management
26
Database Development Process
Database Systems Development
Requirements Specification
User
Requirements Elicitation
Requirements
Conceptual Model
Conceptual Modelling
Logical Model
Logical Modelling
Physical Model
User
Physical Modelling
Database System
Database System Documentation
27
Database Systems and Development
Data Model
DBMS
Database Development
Universe of Discourse
Database
28
Summary Database, DBMS and Data Model
  • A database is a shared collection of data.
  • Surrounding the database we have the shared
    collection of facilities the DBMS. The DBMS is
    portrayed here as having three parts the kernel,
    the interface and the toolkit.
  • Both the DBMS and database adhere to the tenets
    of some data model. The DBMS is used to manage
    all interactions with the database by end-users
    or application programs.
  • The components of database, DBMS and data model
    all contribute to our definition of a database
    system.
  • Database development is the process of
    representing the data needed to support some
    organisational activity in some chosen DBMS.

29
Database Systems Information Systems
Human Activity System
Communications Technology
Information System
Data
ICT System
Software
DBAs
Database System
Hardware
Users
Types
End-Users
Mass Deployment
Application Developers
Decision-Support
Operational
30
System Elements
Environment
Agent
Control Inputs
System
Control
Control Signal
Control Signal
Process
Agent
Agent
Data Inputs
Data Outputs
Physical Inputs
Physical Outputs
31
IT, IS and Human Activity Systems
Human Activity Systems
Information Systems
Information Technology
32
Layers of an ICT System
ICT System
Interface Management Subsystem
Rules Management Subsystem
Communication Subsystem
Transaction Management Subsystem
Data Management Subsystem
Database
DBMS
Database
33
ICT, Information, Human Activity
Human Activity System
Interface
Information System
ICT System
Data
Data Manipulation
Manipulated Data
34
Levels of Data Models
Corporate Data Model
Business Area Data Model
Business Area Data Model
Business Area Data Model
Application Data Model
Application Data Model
Application Data Model
Application Data Mode
Application Data Model
35
Example in terms of a University Setting
University Data Model
Consultancy Data Model
Teaching Data Model
Research Data Model
Enrolment Data Model
Timetabling Data Model
Payroll Data Model
Library Data Mode
Finance Data Model
36
IS Planning and Database Systems
Business Strategy
Information Strategy
Corporate Data Model
Information Systems Strategy
Business Area Data Model
Application Data Model
Information Technology Strategy
37
Types of Database System
Operational Database
Decision-Support Database
Mass-Deployment Database
38
Database Users
End-User
DBMS
Database
DBA
Developer
39
Summary - Database Systems and Information Systems
  • Data is a set of symbols used to represent
    something.
  • Information is interpreted data.
  • Knowledge is derived from information by
    integrating information with existing knowledge.
  • An information system is a system which provides
    information for some organisation or part of an
    organisation.
  • Information systems support human activity
    systems. Human activity systems consist of
    people, conventions and artefacts designed to
    serve human needs.
  • Information technology provides means of
    constructing aspects of modern-day information
    systems.
  • An information technology system is made up of a
    number of subsystems or layers Interface
    subsystem, Rules subsystem, Transaction
    subsystem, Data subsystem.
  • Database models can be produced on at least
    three levels Corporate data models, Business
    area data models, Application data models.
  • In contemporary applications database systems
    tend to support three main purposes production
    databases, decision-support databases,
    mass-deployment databases.
  • Database systems are critical components of a
    number of developing applications within
    organisations data warehouses/ data marts,
    on-line analytical processing, data mining,
    network database applications and universal
    servers.

40
Database Systems ElectronicBusiness
E-Commerce
E-Business
B2C e-Commerce
B2Be-Commerce
Customer Chain
Internal Value Chain
Supply Chain
Supplier
Supplier
Supplier
Value-Chains
Electronic Organisation
Access Device
Employee
Front-End System
Back-End System
Products/Services
Transactions
Data
41
e-Business Environment
Electronic Business
Electronic Commerce
B2C
B2B
Intra-Business
Supplier
Organisation
Customer
Supply Chain
Customer Chain
Infrastructure
Social
Technical
42
Value-Chains
Supplier
Organisation
Customer
Supply Chain
Customer Chain
43
B2B E-Commerce
B2B E-Commerce
Invoicing
Inventory
Procurement
44
B2C E-Commerce
B2C E-Commerce
Advertising
Marketing
Sales
45
Intra-Business E-Business
Intra-business E-Business
Standard Interfaces
Share Knowledge
Integrate Information Systems
46
Internet, Intranet and Extranet
Internet
Extranet
Business Partners
Firewall
Suppliers
Firewall
Intranet
Intranet
Organisation
Intranet
Remote Employees
Distributors
Intranet
Intranet
Firewall
Firewall
47
Electronic Organisation
Electronic Organisation
Access Channel
Access Channel
Front-End System
Front-End System
Back-End System
Access Device
Access Device
Products/ Services
Products/ Services
Partner
Employee
Transactions
Transactions
Data
Access Channel
Access Channel
Front-End System
Front-End System
Products/ Services
Access Device
Access Device
Products/ Services
Back-End System
Supplier
Customer
Transactions
Transactions
48
ICT Infrastructure Trends
Trends
Access Mechanisms
Electronic Delivery
Front-End ICT Systems
Back-End ICT Systems
Front-End/Back-End Systems Integration
Secure Transactions
49
Applications
Applications
Data Warehouses
OLAP
Data Mining
Database Systems and the Web
Universal Servers
50
Summary Database Systems and e-Business
  • Business can either be considered as an entity
    or as the set of activities associated with a
    commercial organisation. Commerce constitutes the
    exchange of products and services between
    businesses, groups and individuals. Commerce or
    trade can hence be seen as one of the essential
    activities of any business.
  • Electronic business or E-business might be
    defined as the utilisation of information and
    communication technologies to support all the
    activities of business.
  • Electronic commerce or E-commerce focuses on the
    use of ICT to enable the external activities and
    relationships of the business with individuals,
    groups and other businesses.
  • Internet commerce or I-commerce is the use of
    Internet technologies to enable E-commerce.
  • Intra-business E-business refers to the changes
    to the internal value-chain that may be affected
    by information and communication technology.
  • The form of electronic commerce associated with
    re-structuring the supply chain is generally
    referred to as business to consumer or business
    to business (B2B) e-commerce.
  • The form of electronic commerce associated with
    re-structuring the customer chain is generally
    referred to as business to customer (B2C)
    e-commerce.

51
Data Management Layer
Interface
Toolkit
Kernel
External Level
CRUD functions
Transaction Management
Parts
Data Dictionary
Conceptual Level
ANSI/SPARC Architecture
Concurrency Control
Functions
Recovery
Internal Level
Administration Utilities
Authorisation
Data Integrity
Database Sub-Language
Data Communication
Data Control Language
Data Integrity Language
Data Definition Language
Data Manipulation Language
52
ANSI/SPARC Architecture
Application Program
Application Program
Query Processor
Application Program
Application Program
User/External Schema A
User/External Schema B
User/External Schema C
User/External Schema D
External/ Conceptual Mapping A
External/ Conceptual Mapping B
External/ Conceptual Mapping C
External/ Conceptual Mapping D
Conceptual Schema
Conceptual/ Internal Mapping
Internal/Physical Schema
Database
53
Kernel and Toolkit
DBMS Toolkit
Interface
DBMS Kernel
Database
54
Functions of a DBMS
Functions
CRUD Functions
Data Dictionary
Transaction Management
Concurrency Control
Recovery
Authorisation
Data Communication
Data Integrity
Administration Utilities
55
Interface
Interface
Data Definition Language
Data Integrity Language
Data Manipulation Language
Data Control Language
56
Interaction between DBMS and Operating System
DBMS Kernel
Operating System
File Manager
Access Mechanisms
System Buffers
Database
Catalog
57
DBMS Kernel
DBA
User
Programmer
DDL Statements
User Queries
Application Programs
DBMS Kernel
DDL Compiler
Query Processor
PreCompiler
Host-Language Compiler
DML Compiler
Data Dictionary Manager
Run-Time Processor
Database Manager
Operating System
Catalog
Database
Stored Transactions
Object Code
58
Database Management Module
Database Management Module
Authorisation Control
Processing Commands
Integrity Checking
Query Optimisation
Managing Transactions
Scheduling Transactions
Managing Recovery
Managing Buffers
59
Summary - The Data Management Layer
  • The ANSI/SPARC architecture distinguishes
    between the external level, the conceptual level
    and the internal level.
  • A DBMS must support the following functions
    CRUD functions, data dictionary, transaction
    management, concurrency control, recovery,
    authorisation, data communication, data
    integrity, administration utilities.
  • We may distinguish between three parts of a
    DBMS kernel, interface and toolkit.
  • The DBMS kernel provides all the central
    functions such as CRUD functions and concurrency
    control.
  • The DBMS toolkit comprises the range of tools
    that can be used in association with a database.
  • The DBMS interface comprises a standard language
    for accessing kernel functions.
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