chapter 4 database management (summary ppt2007)

8/3/2019 Chapter 4 Database Management (Summary PPT2007)

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Database

A collection of related files

TARC DB: student file +

employee file + payment file +result file

File

A collection of related records 1DAC student file

Record

A collection of related fields NAME+ID+TEL

Field

A group of characters N+A+M+E

Byte/character

A group of 8 bits A-Z, 0-9, %,#

Bit

1 or 0


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Separate datafiles are created

and stored foreach

applicationprogram

Traditionalapproach


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Inventory File

Order Entry File

Billing File

Inventory ControlProgram

Order Entry Program

Customer BillingProgram

Secondary storage


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5

Student -File

S_ID Name Address Gender Tel.

S001 Ivy Liew KL Female 012-12345667

S002 Ian Lee PJ Male 016-2345678

S003 Max Teh KL Male 017-9876543

Exam_File

S_ID Name Address Gender Tel Subject Grade

S001 Ivy Liew KL Female 012-12345667 ITS A

S002 Ian Lee PJ Male 016-2345678 ITS B

S003 Max Teh KL Male 017-9876543 ITS A

Traditional ApproachSome data may be duplicated (required extrastorage space)


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Pool of related

data is sharedby multipleapplication

programs

Databaseapproach


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Inventory File /Order Entry File /

Billing File

Inventory ControlProgram

Order Entry Program

Customer BillingProgram

DBMS

Secondary storage


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Student -File

S_ID Name Address Gender Tel.

S001 Ivy Liew KL Female 012-12345667S002 Ian Lee PJ Male 016-2345678

S003 Max Teh KL Male 017-9876543

Exam_File

S_ID Subject Grade

S001 ITS A

S002 ITS B

S003 ITS A

Database ApproachReduce duplication of data (store onlyonce)


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Relational database

2D tables, consists of rows &columns

1) Row = record = tuple = data entity

2) Column = attribute

3) Domain = field name = domain description

4) Primary key => field(s) uniquely identifies therecord

5) Common field => exists in both files to make a

relationship between them


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Student ID Name Address DOB

A0001 Amber Chia Malaysia 12/3/80

A0002 Andy Lau Hong

Kong

31/8/64

A0003 Peter Pan UK 3/1/85

Tuple

(Record)R1R2

Domain(column

description )

Attributes (Columns)Name attribute, Address attribute, DOB attribute

Student_File Relation

primary key


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Types ofdata files

Masterfile

Containing

permanent recordsthat are generally

updated periodically

Transaction

file

Temporary holding file

that holds all changesto be made to themaster file


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DBMS

programs that provide users withtools to add, delete, access, and

analyze data stored in one location

interface between the databaseand its users and other application

programs


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A repository contains data about each

file in the database and each fieldwithin those files

Data Dictionary

Use Query language to retrieve or

select data from a database

File Retrieval and

Maintenance

Allowed database administrators (DA)to specify different access privileges fordifferent users of a DBMS

Data Security

restore the database to a usable form

in case it is damaged or destroyed

Backup and

Security


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Data is organized by the DBMS

and stored only onceReduce duplication data

Reduced data

redundancy

No separate files contain copies of the samepiece of data

Reduce duplicates & inconsistencies inupdating. Thus, improve data integrity

Improved data

integrity

simple commands can begiven to get the requiredinformation

Better & easieraccess to dataand information

The data in a database isshared by the entire

organization

Shared data

chapter 4 database management (summary ppt2007)

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