database management chapter 4. data elements payroll fileremunerations employee database employee...

Database Management

Chapter 4

Data Elements

Payroll file Remunerations

Employee database

Employeerecord1

Name SSN Salary

Employeerecord2

Name SSN Salary

Employeerecord3

Name SSN Salary

Employeerecord4

Name SSN Salary

Text: O’Brien : p. 144

Logical Data Elements

Fieldrepresents an attribute of an entity

RecordSet of attributes that describe an entity

Fileset of records of the same type

transaction file, archive file, ...

Database integrated set of logically related files and the

rules they have to satisfyText: O’Brien : p. 145

Database

Employee database

Payroll data

Training data

Person data

Database Management

User Inquiry

Applications

Database Management System

Corporate database

Request


Example

CARS (model, #cylinders, origin, tax, fee)

Model #cyl origin tax fee Origin tax

------------------------------------------------------ #cyl fee

Rabit 4 Germany 15 30

Mustang 6 USA 0 45

Mirafiori 4 Italy 18 30

Accord 4 Japan 20 30

Cutlass 8 USA 0 60

Laguna 4 France 20 30

BMW 6 Germany 15 45

Velsatis 6 France 20 45

Velsatis 4 France 20 30

Example

Drivers having a driver-no , a name , a home address and a birth-date take out vehicles to make deliveries. A vehicle ( with a unique id-number ) may be taken out of a depot whenever available and kept out for any length of time . It is possible for a vehicle to be taken out more than once on a given day by any driver .

Each time a driver takes out a vehicle , he or she takes out a load made up of any quantity of any number of item types , identified by an item-number. Every time a vehicle is taken out , the driver can incur expenses of allowed type (e.g. fuel cost ).

Each expense type has a code-no. The amount and code-no are recorded each time an expense is incurred .

Any number of stops can be made during the trip . An address of the stop is recorded for each stop , together with the quantity left on that stop for each item type . A driver stops at an address only one during a trip . However, stops can be made at the same address on different trips.

Assignment

The university that has to keep track of student transcripts could use a database structured as follows.

Student(Student Number - Last name - First name - SSSN - Street - Nr - Zip Code - City - State - Country - Phone Number - Birth Date - Gender - Class - Major - Minor)

Department(Depart. Code - Name - Office Nr - Office Code)

Course(Course Code - Course Name - Description - Credits - Department)

Section(Course Code - Section Nr - Instructor - Semester - Year)

Transcript(Student Number - Name - Course Code - Section Number - Grade)

Work with DBMS-software

Operating system

DBMS

Applicationprograms

Databases

DataDictionary

Database development Database inquiry Database maintenance Application development


Dictionary Access


Database Inquiry

Query LanguagesSQL

Select Name, department, salaryFrom Employee, PayrollWhere Employee.number = Payroll.number and Function = “Analyst”.

QBEEmployee Name number department num

Payroll number function salary num “ Analyst”

DBMS

Userinterface

Querylanguage

Reportgenerator

DBMSutilities

Applicationgenerators

Data-dictionaryprograms

Host-languageProgramInterface

DBMSkernel program

Problems with files Data redundancy Non-integrated files Data dependency Other problems

inconsistency integrity

Possible solutions :

database management system• separation of files and applications

• specific database languages

• central dictionary

Characteristics of databases

Redundancy

. storage cost

. multiple update needed

. inconsistency possible

Data independence

The degree on which data structures can be modified

without affecting the related programs

Solution :

Database architecture with three levels

( conceptual, internal , external )

Types of Databases

Operational databases (subject area databases SADB) transaction databases, production databasesemployee database, stock database, ...

Analytical databases ( management databases )data retrieved from external and operational databasesAccessible for OLAP, DSS, management information systems

Data Warehousescontain historical data from various operational and external

databasescentral source for standardized and integrated data for

management and usersdata mart is a limited version for a specific subjectused for data mining


Types of Databases (2)

Distributed databasesmostly for local needs, can be copiesconsistency problemsdistributed over servers related, eventually via WWW or intranet

Personal databases for end usersvarious data gathered by users on their workstationseventual with spreadsheet or DBMS

External databasesoften access chargestatistical , bibliographical

Text: O’Brien : p. 151-153

Types of Databases (3)

Distributeddatabases

End-userdatabases

Data-warehouse

Managementdatabases

Opera-tional

databases

Externaldatabases

Networkserver

Client-PCor NC


Hypermedia DB on the WEB

Client-PCor NC

WEB-browser

Networkserver

Hypermediadatabase

Internetintranetextranet

Web-serversoftware

parts of aWeb-information system


Data Resource Management

Dataadministration

Data Planning

Database Administration

•Policy governing data ownership and access control•Data Resource Requirement Planning•Data model and data architecture

•Strategic and technical database planning•Define applications•Procedures for data retention•Operational procedures

•Physical database•Logical database•Data dictionary•HW and SW


Benefits and Limitations

Benefits of a DBMS reduces data redundancy and integrates datadata accessible from all programs programs not dependent on data formatquery/answer and reporting facilitieseasier application development and programmingbetter integrity and security

Limitations of a DBMS increased complexity of the technologydevelopment of large databases is difficult and expensiveslower than file management systems due to additional layermore sensible for fraud, errors and failures

Technical Principlesof database management

Files

Physical Logical

AB

C

D

E

A

B

C

D

E

Aspects of file usage

File activity

input 2000orders

processing

revenue state

inquiry

Clientfile

10000records

20%

100%

0.01%

AccessibilityEvolution

1 instruction

1 inquiry

What is a database ?

1. A database is a set of data which are modifiable and accessible by a computer program. text, image, voice, structured information.

2. A database is a set of data which are . structured . integrated . non-redundant . shared

It is a source of data for a large number of different applications and for a variety of users.

Database

Employee

Number Name City

STUDIES

Diploma year

CHILDREN

First name Birthday

12 Duval Rome

16 Krols Dublin

38 Smets Berlin

college 87

master math 94

econ 90

Accounting 94

college 91

Bache elec 94

john 120694inge 241198lidy 070296Carl 040894

type

occurrence

Sample file

Supplier file

SNUMBER SNAME STATUS CITY

S1 De Smet 20 London

S2 Janssens 10 Paris

S3 Blanchart 30 Paris

S4 Clark 20 London

S5 Adams 30 Athens

Supplier file with index on city

Supplier file

SNUM LNAME STATUS City




S4 Clark 20 London

S5 Adams 30 Athens

City-index

Athens .

London .

London .

Paris .

Paris .

Index on city and index on status

Status-index

. 10

. 20

. 20

. 30

. 30

Supplier file

LNUM LNAME STATUS CITY




S4 Clark 20 London

S5 Adams 30 Athens

City-index

Athens .

London .

London .

Paris .

Paris .

Non-dense index

SNUM SNAME STATUS CITY S1 De Smet 20 London



S4 Clark 20 London

S5 Adams 30 Athens

Supplier file

S2 .

S4 .

S5 .

block 1

block 2

block 3

File Organization: Indexed-sequential

multi-levelindex blocks

datablocks

BensDoomsFagin

AdamsAlbertBens

BodooClaesCoddDooms

ErnestFagin

AceAdams

AdemarAertsAlbert

BehrBens

Bodoo

parameters - index block size - data block size

Fully Inverted file

SNAME-index STATUS-index City-index Supplier-

file

De Smet S1-> 10 S1-> Athens S5-> S1

Janssens S2-> 20 S1->,S4-> London S1->,S4-> S2

Blanchart S3-> 30 S3->,S5-> Paris S2->,S3-> S3

Clark S4-> S4

Adams S5-> S5

Sample file

SNUMBER SNAME STATUS CITY




S4 Clark 20 London

S5 Adams 30 Athens

Supplier file

Organization with key transformation


0 1

2 3

4 5

6 7

8 9

10 11

12


S500 Adams 30 Athens


S400 Clark 20 London

Hierarchical Database Structure

Departmentdata element

Project Bdata element

Project Adata element

Employee 2Employee 1


Network Database Structure

Department A Department B

Employee 1 Employee 2 Employee 3

ProjectA

ProjectB


Relational Structure

Department D# DName location Manager

D1

D2 D3

D4

D5

Employee E# EName FUNCTION SALARY D#

E1 D1E2 D1E3 D2E4 D3E5 D3


Object Oriented Structure

Attributes•client•status•interestOperations•payment•withdrawal

Attributes•number of withdrawals•Quarterly statement

Operations•calculate interest•print quarterly statement

Attributes•credit limit•monthly statement

Operations•calculate interest•print status

Object class Bank account

Object class Checking account

Object class Saving account

Inheritance


Database Development

1.Data Planning

2. Specification gathering

3. Conceptual design

4. Physical design

5. Logical design


Data Modeling

Entity-relation diagram

EMPLOYEE

MANAGER

STAFFER

FREELANCER

COMPANY CAR

INVOICE

SUPERVISEDby

Allocated

Authorizes

submits


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