meljun cortes - database system/dbms

8/9/2019 MELJUN CORTES - Database System/DBMS

1/53

File SystemsFile Sy

stems

& Databases& Databases

MELJUN CORTES MBA MPAMELJUN CORTES MBA MPA


http://meljuncortes.blogspot.com


2/53

MELJUN CORTES MBA MPAMELJUN CORTES MBA MPAMELJUN CORTES MBA MPAMELJUN CORTES MBA MPA

2

Examples of Use of DatabaseSystems

Banks

Travel Agents

Scientific Data Collection



3/53

3

Introducing the Database

Major Database Concepts

Data and information

Data - Raw facts

Information - Processed data

Data management

Database

Metadata (=Data about data)

Database management system (DBMS)



4/53

4


Database management system (DBMS) DBMS is the software that interacts with the users, application

programs, and the database. Example : IBM DB2, Microsoft

SQL Server, Oracle, MySQL etc.

Data DBMSApplication

Programs



5/53

5


Importance of DBMS

It helps make data management moreefficient and effective.

It provides end users better access to moreand better-managed data.

It promotes an integrated view of

organizations operations -- big picture. It reduces the probability of inconsistent

data.



6/53

6

The DBMS Manages the Interaction

Between the End User and the Database



7/53

7

The Importance of Database Design

A well-designed database facilitates datamanagement and becomes a valuable

information generator.

A poorly designed database is a breedingground for uncontrolled data redundancies.

A poorly designed database generates

errors that lead to bad decisions.




8/53

8

Basic File Terminology

Data Raw facts that have little meaning unlessthey have been organized in some logicalmanner.

Field A character or group of characters

(alphabetic or numeric) that has a specificmeaning. A field might define a telephonenumbers, a birth date, a customer name, ayear-to-date (YTD) sales value, and so on.

Record A logically connected set of one or morefields that describes a person, place, orthing.

File A collection of related records.



9/53


10/53

10

Data Model - A collection of concepts that

can be used to describe the structure ofdatabase.

Database instance Separate location ofmemory reserved for running a specificdatabase

Database Schema- the description of adatabase, which is specified duringdatabase design and is not expected tochange frequently.

Basic File Terminology



11/53

11

A Simple File System



12/53

12

File SystemCritique File System Data Management

File systems require extensive programming ina third-generation language (3GL).

As the number of files expands, systemadministration becomes difficult.

Making changes in existing file structures isimportant and difficult.

Security features to safeguard data aredifficult to program and usually omitted.

Difficulty to pool data creates islands of

information.


13/53

F t


14/53

14

Field Definitions and Naming Conventions

A good (flexible) record definitionanticipates reporting requirements bybreaking up fields into their components.

Example:

Customer Name --> Last Name, FirstName, Initial

Customer Address --> StreetAddress, City, State

F e ystemCritique



15/53

F t


16/53

16

FIELD CONTENTS

CUS_LNAME Customer last nameCUS_FNAME Customer first name

CUS_INITIAL Customer initial

CUS_AREACODE Customer area code

CUS_PHONE Customer phone

CUS_ADDRESS Customer street address or box number

CUS_CITY Customer city

CUS_STATE Customer state

F e ystemCritique


F t


17/53

17

Data Redundancy:

Uncontrolled data redundancy sets thestage for

Data Inconsistency (lack of data integrity)

Data anomalies

Modification anomalies

Insertion anomalies

Deletion anomalies

F e ystemCritique


D t


18/53

18

The Database System Components

Hardware

Computer

Peripherals

Software

Operating systems software

DBMS software Applications programs and

utilities software

Data aseSystems


D t


19/53

19


People

Systems administrators (SA)

Database administrators (DBAs) / Owner (Dbo)

Database designers Systems analysts and programmers

End users

Procedures (sp)

Instructions and rules that govern the designand use of the database system

Data

Collection of facts stored in the database

Data aseSystems


D t


20/53

20


The complexity of database systems dependson various organizational factors:

Organizations size

Organizations function

Organizations corporate culture

Organizational activities and environment

Database solutions must be cost effective ANDstrategically effective.

Data aseSystems


Data ase


21/53

21

Types of Database Systems

Number of Users

Single-user

Desktop database

Multiuser

Workgroup database

Enterprise database

Scope/limitation

Desktop

Workgroup

Enterprise

Data aseSystems


Data ase


22/53

22

The types of Database Systems

Location

Centralized Database

Distributed Database

Use

Transactional (Production)

Decision supportData warehouse

Data aseSystems

MELJUN CORTES MBA MPAMELJUN CORTES,MBA,MPAMELJUN CORTES,MBA,MPAMELJUN CORTES,MBA,MPA Data ase


23/53

23

DBMS Functions

1.Data Dictionary Management

2.Data Storage Management

3.Data Transformation and Presentation

4.Security Management

5.Multi-User Access Control

6.Backup and Recovery Management

7.Data Integrity Management

8.Database Access Languages (DDL and DML) andApplication Programming Interfaces

9.Database Communication Interfaces

Data aseSystems


b d l


24/53

24

A database model is a collection of logical constructsused to represent the data structure and the datarelationships found within the database.

Two Categories of Database Models

Conceptual models focus on the logical nature ofthe data representation. They are concerned withwhatis represented rather than how it is

represented.

Implementation models place the emphasis on howthe data are represented in the database or on howthe data structures are implemented.

Database Models



25/53

25

Three Types of Relationships

One-to-many relationships (1:M)

A painter paints many different paintings, but each oneof them is painted by only that painter.

PAINTER (1) paints PAINTING (M)

Many-to-many relationships (M:N) An employee might learn many job skills, and each job

skill might be learned by many employees.

EMPLOYEE (M) learns SKILL (N)

One-to-one relationships (1:1)

Each store is managed by a single employee and eachstore manager (employee) only manages a single store.

EMPLOYEE (1) manages STORE (1)

Database Models



26/53

26

Three Types of ImplementationDatabase Models

Hierarchical database model

Network database model

Relational database model

Database Models

MELJUN CORTES MBA MPAMELJUN CORTES,MBA,MPAMELJUN CORTES,MBA,MPAMELJUN CORTES,MBA,MPA M d l


27/53

27

Hierarchical Database Model

Basic Structure

Collection of records logically organized to conformto the upside-down tree (hierarchical) structure.

The top layer is perceived as the parent of thesegment directly beneath it.

The segments below other segments are thechildren of the segment above them.

A tree structure is represented as a hierarchicalpath on the computers storage media.

Models



28/53

Types of Database Data Models -

Hierarchical

The first database systems developed were

hierarchical

Databases using the hierarchical model

usephysical pointers to link records

MELJUN CORTES MBA MPAMELJUN CORTES,MBA,MPAMELJUN CORTES,MBA,MPAMELJUN CORTES,MBA,MPA


29/53

29

Pointer Based

Linkages BetweenEntities

Location Prof# Name Office# 1st Stude

P10 J13 Jones SB312 P203

P11 M7 Morgen BA 218 P200P12 D23 Davis SB 106 P201

Location Stud# S_name

Class

Standing

Next

Prof_Stud

P200 1234 Smith Fr P202

P201 4678 Davis So P204P202 2943 Evans Fr P206

P203 1874 Allen Jr P205

P204 4017 Lloyd Fr *

P205 2318 Marx Sr P207

P206 6021 Keen So *

P207 5503 Watts Jr *

Pointers give thephysical location of a

related set of data, thelocation values(P10, P201, etc.) in ourexample are meant torepresent this type ofphysical location. Realpointers usually

indicate a displacementin a file. Instead of theP203 value in the firstprofessor record

we would see anindicator that therelated data begins at

the 4028th byte of thefile that stores studentMELJUN CORTES MBA MPAMELJUN CORTES MBA MPA


30/53

30

Location Prof# Name Office# 1st StudentP10 J13 Jones SB312 P203

P11 M7 Morgen BA218 P200

P12 D23 Davis SB 106 P201

Location Stud# S_name

Class

Standin

g

Next

Prof_Stud

P200 1234 Smith Fr P202

P201 4678 Davis So P204

P202 2943 Evans Fr P206

P203 1874 Allen Jr P205P204 4017 Lloyd Fr *

P205 2318 Marx Sr P207

P206 6021 Keen So *

P207 5503 Watts Jr *

Pointer Based LinkagesBetween Entities



31/53


Hierarchical

The first database systems developed were

hierarchical


use physical pointers to link records

allow only hierarchical relationships



32/53

32

Hierarchical

A hierarchical relationship is onewhere each entity at a lower levelof the hierarchy is related to onlyone type of entity at a higherlevel of the hierarchy (a higherlevel entity can be linked to twoor more lower level childentities)

AA

BB CC

MELJUN CORTES MBA MPAMELJUN CORTES MBA MPAMELJUN CORTES MBA MPAMELJUN CORTES MBA MPA Types of Database Data


33/53

Types of Database Data

Models -HierarchicalThe first database systems developed were hierarchical


use physical pointers to link records

allow only hierarchical relationships

+Hierarchical databases provide very efficient high-speed retrieval

They are difficult to modify as an organizations data

needs change It is difficult to use them to represent non-

hierarchical relationships

(essentially you must create multiple linkedhierarchical databases in order to representnetwork relationships)




34/53

34


Models -NetworkThe next type of data model developed was the network model

Databases using the Network model use physical pointers to link records - like the hierarchical model

do support network as well as hierarchical relationships

+Network databases provide very efficient high-speed retrieval

+Can represent network, as well as, hierarchical relationshipseasily

Are difficult to modify as an organizations data needs change

Have complex pointer structures which can be difficult tomanipulate and hard for end-users to understand.



35/53

35

A network relationship is one in whichan entity at a lower level can be linkedto two or more entities at a higherlevel.

E.G. - an order is related to both acustomer who placed it and asalesperson who made the sale

The hierarchical model does notsupport network relationships.

To capture them a second database

would have to be created and linkedto the first.

Network Relationships

AA

BBCC



36/53

36


Relational Relational Database Model

Basic Structure

RDBMS allows operations in a human logicalenvironment.

The relational database is perceived as acollection of tables.

Each table consists of a series of row/columnintersections.

Tables (or relations) are related to eachother by sharing a common entitycharacteristic.

The relationship type is often shown in arelational schema.

A table yields complete data and structuralindependence.



37/53

37

Repetition of Identifying

Data to Link Related Data

Prof# Name Office#

J13 Jones SB312

M7 Morgen BA218

D23 Davis SB 106

Stud# S_name

Class

Standing Prof#

1234 Smith Fr M7

4678 Davis So D23

2943 Evans Fr M7

1874 Allen Jr J13

4017 Lloyd Fr D23

2318 Marx Sr J13

6021 Keen So M7

5503 Watts Jr J13



38/53

38

Linking Relational Tables



39/53

39

Relational Database

Model- Advantages Structural independence

Improved conceptual simplicity

Easier database design, implementation, management,

and use Ad hoc query capability (SQL)

Powerful database management system

Disadvantages

Substantial hardware and system software overhead

Possibility of poor design and implementation

Potential islands of information problems



40/53

40

A Relational Schema



41/53

41

Entity-Relationship Data Model

It is one of the most widelyaccepted graphical data modeling

tools.

It graphically represents data asentities and their relationships ina database structure.

It complements the relational datamodel concepts.

Entity-Relationship Data

Model



42/53

42

Entity Relationship Data Model

Basic Structure

E-R models are normally represented in anentity relationship diagram (ERD).

An entity is represented by a rectangle.

Each entity is described by a set of attributes.An attribute describes a particularcharacteristics of the entity.

A relationship is represented by a diamondconnected to the related entities.

Model



43/53

43

The ER Diagram

Complements the relational data model concepts

Represented in an entity relationship diagram (ERD)

Based on entities, attributes, and relationships

MELJUN CORTES MBA MPAMELJUN CORTES MBA MPAMELJUN CORTES MBA MPAMELJUN CORTES MBA MPA -


44/53

44

Entity-Relationship Data Model

Advantages

Exceptional conceptual simplicity

Visual representation

Effective communication tool

Integrated with the relational database model

Disadvantages

Limited constraint representation

Limited relationship representation

No data manipulation language Loss of information content

-Model

MELJUN CORTES MBA MPAMELJUN CORTES MBA MPAMELJUN CORTES MBA MPAMELJUN CORTES MBA MPA Types of Database Data


45/53

45


Models - Object Oriented Object-Oriented Database Model

Basic Structure

Objects are abstractions of real-world entities or events.

Attributes describe the properties of an object.

Objects that share similar characteristics are grouped inclasses.

A class is a collection of similar objects with sharedstructure (attributes) and behavior (methods).

Classes are organized in a class hierarchy.

An object can inherit the attributes and methods of theclasses above it.


46/53

46

Object-Oriented Database Model

Characteristics

An object is described by its factual content.

An object includes information aboutrelationships between the facts within theobject, as well as with other objects.

An object is a self-contained building block

for autonomous structures.


Models - Object Oriented



47/53

47

Object-Oriented Database Model

Advantages

Add semantic content

Visual presentation includes semantic content

Database integrity

Both structural and data independence

Disadvantages

Lack of OODM standards

Complex navigational data access

Steep learning curve

High system overhead slows transactions


Models - Object Oriented



48/53

48

A Comparison: The OO Data Model and

the ER Model

MELJUN CORTES MBA MPA


49/53

49

Centralized Versus Decentralized

Database Systems

Centralized Database with remote Access

All processing to support the database system is

performed on a central computer. Only input/outputfunctions are performed remotely.

(If PCs are used for remote access theyoperate in terminal emulation mode anddo not perform processing)



50/53

Centralized Database with Remote

Access

Terminal

Only I/Odone here

Terminal

Only I/Odone here

Terminal

Only I/Odone here

Terminal

Only I/Odone here

Central DBComputer

All processingrelated to DBSystem done

here


51/53

51

Centralized Database with remote Access All processing to support the database system is

performed on a central computer. Only

input/output functions are performed remotely. Client-Server Database

All data reside on a central server

Core database management processing isperformed on server

Application files and processing to request data,manipulate results and manage the userinterface is performed on client computers

Centralized Versus DecentralizedDatabase Systems



52/53

Client-Server Database System

Server

ComputerAll Database

access, retrievaland, manipula-tion processesperformed here

Client Comp

Syntax checksof SQL stmts.Manipulation- presentationof retrieved

data done here

Client Comp

Syntax checksof SQL stmts.Manipulation- presentationof retrieved

data done here



53/53

53

References

ROB, P. AND CORONEL, C., 2004, Database

Systems. 6th Ed., Thomson Course Technology

meljun cortes - database system/dbms

Documents