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Objectives
File Processing System
Data Base Management System
Different types of DBMS
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Data Vs Information
What is data? facts concerning things such as people, objects,
events, etc.
EX : Marks 80 %, 75 %, 65 %, 99%
What is information? data that has been processed and presented in a
form suitable for human interpretation.
Ex : Marks of a Student No. 1998 is 80% inRDBMS course.
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Data Vs Information
To derive information from data weneed to Store and Process.
Need systems support to easily
Store
Retrieve
and Modify data
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Traditional Method of Storage
Files
File Management System (O/S)
Application
ProgramsP1 P2 P3 P4
001 Chandu Enr
002 Steve Pdn
003 Hema Enr
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Files in an Organization
Data File
Master files
Transaction files
Others
Computer program files Backup files
Specialized files: Index files & log files.
Other important files
Object File
Library File Executable File / Load Module
Temporary Files
What is the significance of each type of file ?
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Ways of storing data in Files4176 Aniruddha Sarkar CAPS
4181 Manoj Saha WENA
4183 Moushumi Dharchoudhury CENA
4203 Suryanarayana D.V.S.S. SONA
4204 Vivek Rai CAPS
4176 AniruddhaSarkar CAPS
4181 ManojSaha WENA
4183 MoushumiDharchoudhury CENA
4203 SuryanarayanaD.V.S. SONA
4204 VivekRai CAPS
4176,Aniruddha Sarkar,CAPS,4181,Manoj Saha,WENA,4183,Moushumi
Dharchoudhury,CENA,4203,Suryanarayana D.V.S.,SONA,4204,Vivek Rai,CAPS
Predefined length
Uses space/commas as character
separators
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DATADEPENDENCY
INCONSISTENCY
REDUNDANCY
LOSS OF
FLEXIBILITY
MULTIPLE
FILES
UPDATE
PROBLEM
Problems with File approach
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Introduction To
Data Base ManagementSystem?
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Introduction to DatabaseManagement Systems
The most traditional/common way of managing data is to store them infiles.
File processing system
Files can be
Sequential
Indexed
Relative
In this kind of scenario, the files are managed directly by the operatingsystem services
The primary focus here is to manage the files effectively rather thanthe contents of them
Though this mechanism is very good, it has many draw backs
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What are the problems in FileProcessing
File processing system manages files rather than the data in them.
How does it affect me ?
File Processing System does not provide effective security
Either the entire file is secured or it is not
Some part of the file cannot be secured
record or column level security is not available
Any program which works with files has to know the physical as well asthe logical structure of the file
Any change in either physical or logical structure of the file, makesit necessary for the program to be rewritten
Physical Data Dependence
Logical Data Dependence
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Introduction to DBMS
Data Base Management System
A DBMS is a special set of software which is usedto manage data (information)
Following are some of the important functionsof a DBMS
Data is Accurate (Accuracy)
Data is provided within a timeframe (Timeliness) Only required data is provided (Relevancy)
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The Database
Database is a set of inter-related data
stored centrally on any online mediumwith controlled redundancy which canbe shared by multiple application /
users with a practical ease.
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A database is a repository of integrated &
shared data
The Database
Computer based record-keeping system
Collection of interrelated (persistent)
dataRecords & maintains data
Represents real world objects
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DBMS and File ProcessingSystem
A database is a collection of data
All the information is available centrally
A file is a collection of bits and piecesstored together as a single entity.
A database system internally relies on the
file processing system to manage its data Externally to the user, he feels that he is
storing data, rather than a file
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Advantages of Database
Redundancy can be reduced
Inconsistency can be avoided
Sharing of DataStandards can be enforced
Security restrictions can be applied
Integrity of data can be maintainedConflicting requirements can be balanced
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Database ManagementSystem
Interface between user & DB
Constructs, expands & maintains the DB
File creation / deletion
Adding, deleting & modifying records
Selecting records (queries)
Manages one or more databasesHigher level of abstraction
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Application Programs usingDBMS Services
Application
Programs
DBMS
File System
Storage
A1 A2 A3
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App. pgmmer
Interface thro High
level language
OS (File Mgr, Disk Mgr)
End userApp. pgmmer
Interface thruQuery
OS (File Mgr, Disk Mgr)
DBMS
Where does DBMS fit ?
End user End user
Physical Storage
(Hardware)
Physical Storage
(Hardware)
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DBMS Architecture
Conceptual level
Internal level
External
View
External
View
External
View
DBMS interface
DBMS interface
DISK(s)
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Emp. Name
Emp. Address
Emp. NameEmp. SSNEmp. AddressEmp. Annual_Salary
Emp. Name : string(25)Emp. SSN : Integer, Primary key
Emp. Address : string(50)Emp. Skill : String(6)Emp. Annual_Salary : Dec(9,2)
Name : string, length 25, offset 0SSN : Integer, length 4, offset 25,
INDX unique indexAddress : string, length 50, offset 29Skill : String, length 6, offset 79Annual_Salary : dec (9,2),length 5, offset 85
External
view
Conceptual view
Internal view
User1
User2
DBA
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Interaction with DBMS
A user issues an access request using someparticular sub-language (typically SQL)
The DBMS intercepts the request & interpretsit
The DBMS inspects, in turn, the externalschema, the external/conceptual mapping,the conceptual schema, theconceptual/internal mapping & storagestructure definition
The DBMS performs the necessary operationson the stored DB
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Data sub-languageGenerally data sub-language (DSL) is embeddedin a host language like C or COBOL
Data Definition Language (DDL) :defines & describes the DB objects
Data Manipulation Language (DML) :
supports the manipulation or processingsuch objects
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Users of a DBMS
Database Administrator(DBA)
Database Designer
Application Programmer & SystemAnalyst
End users
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Characteristics of DBMS
Data independence
Speedy handling of spontaneous
information requestsNon-Redundancy
Versatility in representing relationships
between data itemsSecurity protection
Real Time accessibility
f d ff
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Comparison of differentsystems
For better understanding we have broken the different types of data processingsystems into the following four categories
Rudimentary I/O software
Programs working with flat files
COBOL or C language
File Storage with Access Method
Programs working with file managers like VSAM or ISAM or Btrieve
COBOL or C Language
Database Management System
Programs written in COBOL or C or Java to work with RDBMS like DB2,Oracle or Sybase
Programs written in COBOL or RPG to work with Hierarchical andNetwork DBMS
Lot of efforts in generating reports
Advanced Management Tools
Use of Rapid Application Development Tools like Report Generator orForms Generator for creating large applications
C i f iff
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Comparison of DifferentSystems
Rudimentary I/OSoftware
File Storage with Accessmethod
Database Management Advanced ManagementSystems
No independence Storage Independence Physical DataIndependence
Logical Data Independence
Applicationprogrammer designsthe physical data
layout and embeds itinto his program
Storage units can bechanged withoutchanging program
Physical data structurecan be changed withoutchanging programs
Global logical data bechanged without changingthe program
Applicationprogrammers view ofthe file is same as thephysical structure
Applicationprogrammers view ofthe file is converted intophysical file by thesoftware
Physical databasestructures are completelyseparated from thelogical structures
Schema, subschema andphysical data is absolutelyseparate
Programmer usessimple files
Application programmermore concerned withstructures andaddressing
Application programmermore concerned withstructures andaddressing
Application programs arecompletely insulated fromthe data structures
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Comparison of Different SystemsRudimentary I/O
Software
File Storage with
Access method
Database
Management
Advanced
ManagementSystems
Entirelysequential files
Sequential fileswith some directaccess
Direct access filesfor someapplications
Direct access to alllive data
Data accessed
with primary key
Data accessed
with primary aswell as secondarykeys
Generalized
searching facility
Generalized
searching facility
No attention todata security
Securityproceduresapplied to
individual datafiles
Securityprocedures appliedto individual data
files
Corporate worldwide security
No teleprocessing
Simple remoteinquiry
Remote data entryand inquiry
Complete interactiveprocessing remotely.Computer networksand distributeddatabases
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Different types of DBMS
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Hierarchical ModelP1 Nut Red 12 London
S1 Jones 10 Paris 300
S2 Smith 20 London 300
P2 Bolt Green 17 Paris
S1 Jones 10 Paris 300
S2 Smith 20 London 400
S3 Blake 10 Paris 200
P3 Screw Blue 12 London
S1 Jones 10 Paris 300
P4 Screw Green 17 Paris
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Hierarchical Model
In a hierarchical model a tree likestructure is maintained
For each parent record, there can bemany siblings
The record at the top is called the root
The root may have any number ofdependants. Each of which may havelower level dependants.
D b k f Hi hi l
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Drawbacks of Hierarchicalmodel
Insert It is not possible to insert a supplier who is not
supplying a part currently
Delete Deleting part information will also delete
information about all the suppliers below it
Update If you need to update any supplier information,
you need to search the entire database for thesame supplier and update all the records for thesame supplier.
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Network Model
S1 Smith 20 London S2 Jones 10 Paris S3 Blake 10 Paris
P1 Nut Red 12 London P2 Bolt Green 17 Paris P3 Screw Red 12 Rome P4 Screw Green 10 Paris
300200 500 100
300
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Network Model
In case of network model, data isrepresented by records and links
Many to Many relation can be expressedeasily in a network model
This is not possible in hierarchical model
Records are linked to each other usingconnectors
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Advantages of Network model
Insert You can simply insert a new part or supplier
without any need to establish any link
Delete Deleting a supplier or a part does not delete
recursively
Similarly, just by deleting the connector, the link
between supplier and parts can be broken.Update Since suppliers and parts occur only once,
updating requires only change to be made to asingle record rather than searching and updatingmany records
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Relational ModelS# SNAME STATUS CITY
S1 Smith 20 London
S2 Jones 10 Paris .
S3 Blake 30 Paris .
S
P# Pname Color Weight City .
P1 Nut Red 12 London .
P2 Screw Red 17 Paris .
P3 Bolt Blue 17 Rome .
P4 Screw Yellow 14 London .
P
S# P# Qty
S1 P1 200
S1 P2 100
S1 P3 300
S1 P4 230
S2 P2 100
SP
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Relational Model
In relational model the data is simplyrepresented in the form of tables
If you compare, these three tables closely
resemble sequential filesCompared to the other two models, relationalis simple to understand
There are no links or pointers which connectdifferent tables
The model is called relational because it usesrelational algebra to represent and manage
information
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More On Relational Model
Each row is called as a tuple
Each column is called as a attribute
Domain It is a set of permissible values that can be stored
in an attribute
This feature is not available in the other models
Relational model provides a set of operatorsto the user. Using these operators, the usercan perform any operations on the tables.
Advantages of Relational
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Advantages of RelationalModel
Insert Adding a new supplier or a part is not a problem.
They are independent entities
If you want to represent a relation betweensupplier and parts, then insert a tuple in SP table.
Delete Delete operations are independent of other tables
Update Updating supplier or part information is very
simple
Management Systems
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Management Systems(RDBMS)
The basic functionality of RDBMS wasconceptualized by Dr. E F Codd, when he wasworking for IBM
He laid down certain principles which govern thefunctioning of any RDBMS
In 1974, the first standard of SQL was also
developedAlso C J Date from IBM also contributedtowards standardization of RDBMS
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Commercial Packages
Hierarchical Model : IMS
Network Model : IDMS
Relational Model : DB2, ORACLE,
SYBASE,ACCESS,INFORMIX, SQL Server
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End of Session 1