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8/8/2019 Cs371 Lecture 01
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File Systems and Databases
Lecture 1
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Files and Databases
File: A collection of records or documentsdealing with one organization, person, area orsubject (Rowley)
± Manual (paper) files
± Computer files
Database: A collection of similar records with
relationships between the records (Rowley) ± Bibliographic, statistical, business data, images,
etc.
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Introducing the DatabaseIntroducing the Database
Major Database Concepts
± Data and information
Data - Raw facts
Information - Processed data
± Data management & Data Administrator
± Database & Database Administrator
± Metadata
± Database management system (DBMS)
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Contents of the CUSTOMER File
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Table 1.1 Basic File Terminologyata ³Raw´ facts that have little meaning unless they have beenorganized in some logical manner. The smallest piece of datathat can be ³recognized´ by the computer is a singlecharacter, such as the letter A, the number 5, or somesymbol such as; µ ? > * +. A single character requires onebyte of computer storage.
Fiel A character or group of characters (alphabetic or numeric)that has a specific meaning. A field might define a telephonenumbers, a birth date, a customer name, a year-to-date(YTD) sales value, and so on.
ecor A logically connected set of one or more fields that describesa person, place, or thing. For example, the fields that
comprise a record for a customer named J. D. Rudd mightconsist of J. D. Rudd¶s name, address, phone number, dateof birth, credit limit, unpaid balance, and so on.
File A collection of related records. For example, a file mightcontain data about ROBCOR Company¶s vendors; or, a filemight contain the records for the students currently enrolledat Gigantic University.
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Limitation of Computerized File-basedApproach
Separation and Isolation of data
Eac applicati ai tai s its s t f ata.
s rs f applicati ay awar f pot tially
s f l ata l y ot r applications.
Duplication of data (data redundancy)
Same ata is el y iff er ent files.
Limited Data Sharing
No centr alized contr ol of data
Lengthy Development Times
Pr ogr ammersmust design t eir own file f or mats
Excessive Pr ogram Maintenance
80% of inf or mation systems udget
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Limitation of File-basedApproach
Accessibility
Data is stor ed using pr ogr ams t at ar e written in
diff er ent languages and f or mat
annot easily access ot er files due to incompati le file
f or mat.
No contr ol over access and manipulation of data eyond
t at imposed y application pr ogr ams.
Hard Coded Queries (Data dependence)
ile str uctur e and all definition of data ar e defined in t e
application pr ogr am code.
ny new r equir ement needs a new pr ogr am.
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Database Processing
System
SOLUTION:SOLUTION:
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Data Administrator
Data Administrator is responsible for the
entire data of an organization. He normally
develops the overall functional requirements
for the databases being used in offices.
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Database Administrator
The Database Administrator is responsible for
the design, implementation, operations,
management and maintenance of the
database.
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Database Management System (DBMS)
A collection of pr ograms t at enables users to define, cr eate
and maintain and contr ol access to t e database.
ener al-pur pose softwar e system t at f acilitates t e pr ocessesof def ining, constructing and manipulating databases f or
various applications.
Def ining - specif ying data types, str uctur es, constr aints.Constructing - storing of data
Manipulation - quer ying, updating and r eporting.
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Popular DBMS In The Market
Sybase SQL Anywhere
Informix Dynamic Server
Borland Interbase
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The DBMS Manages the Interaction
Between the End User and the Database
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Database SystemsDatabase Systems
The Database System Components
± Hardware
Computer
Peripherals
± Software
Operating systems software
DBMS software
Applications programs and utilities software
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Database SystemsDatabase Systems
The Database System Components
± People
Systems administrators
Database administrators (DBAs)
Database designers
Systems analysts and programmers
End users
± Procedures
I
nstructions and rules that govern the design and use of the databasesystem
± Data
Collection of facts stored in the database
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Database Systems
Types of Database Systems
± Location
Centralized
Distributed
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Data Independence
Logical Data Independence:
The capacity to change the conceptual schema without having to change
the external schemas and their associated application programs.
Physical Data Independence:
The capacity to change the internal schema without having to change theconceptual schema. For example, the internal schema may be changed
when certain file structures are reorganized or new indexes are created to
improve database performance