Data types: A data type is
classification of various types of data Examples of data. Data types are
integer, float, character, string (A group of characters)
Integer: An integer data type can hold
a whole number.
Float: Float values are also called
real data valves are stored in a single memory location.
Logical data type: It consists of 2
values is stored by true/false.
Characters: Character data type when we
went to include letters, numbers, spaces, symbols and punctuations, the size is
1 byte. A few data types are corrective field, data fields, integer fields and
text fields.
Data processing: Data (15) a collection
of facts, un organized to be organized into useful information. We give data as
an input and we get the output can be used to help people make decisions it is
called information data processing system is used to include the resources such
as people, procedures and devices that are used to accomplish the processing of
data for producing desirable output.
Data storage
hierarchy:
Field: A field is a meaning full
collection of related characters.
Ex: S.No,
S.name….. etc.
Record: Fields we normally grouped
together to form a record.
Ex: Field
Character
 |
Field
or Data
 |
Record
File
File organization:
System designers choose to organize, access and process records and files in
different ways depending on the type of application and the needs of users.
There are 3 commonly used file organizations.
1. Sequential
2. Direct
3. Indexed
sequential organization
The selection of a particular organization depends upon the
type of application. File organization requires the use of some key field,
identifying value i.e. found in every record in the file.
Serial file
organization: Records are arranged one after another in no particular order
serial organisation is commonly found with transaction data where records are
created in a file in the order in which transactions takes place.
For example: Daily
purchase.
Sequential file
organization: Records are stored one after another in an ascending (or)
descending order determine by the key field of the record.
Ex: Payroll
To access a record, the computer must read the file in
sequence from the beginning.
Advantages:
1.
Easy to understand, maintain and organize.
2.
There is no overhead in address generation.
3.
It is more efficient and economical file organisation
Disadvantages:
1.
Active ratio is very low.
2.
Transactions must be stored and placed in sequence
prior to processing.
3.
Data redundancy (duplication of data) is typically
high.
Direct access file
organization: Allows immediate access to individual record on the file, the
records are stored and retrieved using a relative record number, which gives
the position of the record in the file. The most widely used direct access
methods are
† Self Direct addressing: Key is used as
its relative address. Therefore we can complete the records address
directly from the record key and the physical address of the first record in
the file. It is a fixd length
record in a sequential file and in which the keys are from a complete range of
consecutive records.
Key Record
F1 1-80
F2 81-130
Advantages: No
need to store an index
Disadvantages:
1. Records must be of fixed length.
2. If some records are deleted their storage space remains
empty.
Indexed sequential
file organisation (ISAM):
It is an hybrid between sequential and direct access. The
records with in the file are stored sequentially but direct access to individual
record possible.
This type of file organize is suitable for batch processing
and online processing
Advantages:
1.
Efficient and economical use.
2.
Activity ratio is very high.
3.
Permits direct access processing of records in a
relatively efficient way when the activity ration is low.
Disadvantages:
1.
Access to records may be slower than direct files.
2.
Less efficient in the use of storage space.
† Random access method: Transactions can
be processed in any order and written at any location to store
file. The desired records can be directly accessed using randomizing procedure.
Advantages:
1.
Retrieval of record is quick and direct.
2.
Need not be stored in sequence.
3. It is suitable interactive online
applications like banking, air line and railway reservation system.
Disadvantages:
1.
Address generation over head is involved for accessing
each record due to hashing function.
2.
Less efficient than sequential file organisation.
† Best file organisation: The following
factors are to be considered for the best file organisation.
1.
File volatility
2.
File activity
3.
File interrogation
4.
File size.
File volatility: No.
of additions and deletions to the file in given period of time.
File activity: It
is the proportion of master file records that are actually used (or) accessed
in a given processing run. In real time file, where each transaction is
processed immediately at a time, only one master file record is accessed (ATM
transaction). If requires a direct access method.
File interrogation: File
interrogation means retrieval of individual records must be fast to support a
real time operation such as airline reservation then some kind of direct
organisation is required.
File size: Immediate
response must be organized by direct access method in large file system. On the
other hand with small files it may be more efficient to search the entire file
sequentially.
Database Management
System (DBMS):
A database management system is a set of software
programmes, that controls a organisation storage, management and retrieval of
data in a data base. A data base is repository for related collection of data
for example an address book can be a data base where names, address, phone No.
of friends on business contacts are stored.
Name address Friend
Ph.No. Business
contact
Management problems of
file processing:
Data needed for each user application was stored in
independent data files processing consisted of using separate computer
programme that updated these independent data files and used them to produce
documents and reports by separate user application. There are several problems
in file processing approach.
1. Data duplication
2. Independent data files include a lot of duplicated data,
the same data is recorded and stored in several files.
3. This data integration: Independent files makes it
difficult to provide end users with the information for adhoc requests that
requires accessing data stored in several different files. It is time consuming
of expensive for the organisation.
Data dependence:
In file processing system, major components of a system are
1. Organisation
of files
2. Their
physical location on storage
3. Hardware
4. Application
software
The above components are used to access these files depend
on one another in significant ways.
Data integrity &
Security: There are certain integrity constraints defined in DBMS to
protect an unauthorized access to the data in the databases. For example, when
inserting the data for a particular field, say salary for an employee data
base. It cannot be null. It does not allow the user to leave the field blank,
thus providing integrity and security on the data base.
Solutions for
Database Management:
File processing system.
1.
Reduce data redundancy and inconsistency
2.
Enhance data integrity and security
3.
Provide logical and physical data independence
4.
Improved data sharing
5.
Low cost of developing and maintaining system
What is a data Base?
A data base is a computer file that uses a particular file
organisation to facilitate rapid updating of individual records, simultaneous
updating of related records, easy access to all records by all processed data.
Explain the
architecture of DBMS:-
The following are the 3 levels architecture
1.
External (or) user view
2.
Conceptual (or) global view
3.
Internal (or) Physical view
External (or) user
view:
1.
It is the highest level of data abstraction
2.
It includes only those portions of data base which is
concerned to the user
3.
It describes by means of external scheme
Global or Conceptual
View:
1.
All data base entitles and relationships among them are
included.
2.
Single view represents the entire data base.
3.
It describes all records, relationships and
constraints.
Internal (or)
physical view:
1.
It is the lowest level of data base abstraction
2.
It indicates how data will be stored.
3.
It describes data structure and access method.
4.
It is closest to the physical storage method.
Schema: Moving
unordinary file management to data base system is to separate all data
definitions from the applications, programmes and to consolidate them into a
separate entity called schema, the indication of the logical relationship
between various components of the data base, there are 3 types of schemas
1.
Physical schema (lowest level)
2.
Logical schema (intermediate level)
3.
Sub-schema (highest level)
Data independence: It
is an ability of a database to modify a table definition at one level without
affecting the next higher level, is called data Independence. It means that
when the table is changed at one level and the next level remains unchanged.
There are 2 types of data independence.
1.
Physical data Independence
2.
Logical data Independence
Physical data
Independence:
There is no need to change the conceptual schema, changes in
internal schema is needed by upgrading storage structure and to improve the
performance of the system.
Logical data
independence:
There is no need to change in the external scheme we can
change in the conceptual schema by adding, deleting, updating the records in
the data base.
Parts of database
management system:
The data base management system base major parts
1.
Data
2.
Hardware
3.
Software
4.
User
Data: Most
organizations generate, store and process a large amount of data. The data acts
as a bridge between hardware, software and users. We access it directly through
some application programmes.
Hardware: It
consists of secondary storage device such as magnetic disk, Magnetic tape, CD,
DVD for storing and retrieving the data in a fast and efficient manner.
Software: DBMS
acts as a bridge between user and the data base, we use SQL or application
software’s to do the operations on the data base like insertion, deletion and
up-dation.
User: The broad
classes of users are
a)
Application programmers and system analysts.
b)
End-user.
c)
Data base administrator.
d)
Data base designer.
System analyst: Determines the requirements of End user.
Application
programmers: The programmers implement these specifications as programmes
and the test debug document and maintain the transactions.
End users: There
are the people who require access to the data base for updating and generating
reports.
Database
Administrator: Is responsible for authorization access, coordination,
monitoring and for acquiring the needed software and hardware resources to the
database.
Database designers:
These are responsible for choosing appropriate structures to represent and
store this data.
Relationships in
database: It is a complex task to identify relationship among records in a
large database, the various types of relationships are
i.
One-to-one relationship as in a single parent record to
a single child record or husband record to wife.
ii.
One-to-many relationship single parent records to a
single child record.
iii.
Many-to-many relationships: Two or more parents records
to two or more child records.
Data base structures:
Database management systems are designed to use 3 database structures to
provide easy access to information stored in databases and their relationships
logically.
The 3 database structures are
i.
Hierarchical database structure
ii.
Network database structure
iii.
Relational database structure
Hierarchical database
structure: Records are logically organized into a hierarchical of
relationship. A hierarchically structured database is arranged logically in an
inverted tree pattern. All records in hierarchial is called as “NODES”.
Hierarchical data structure implements one-to-one and
one-to-many relationship.
Features of
Hierarchical database:
i.
Data bases are less flexible than other database
structures. Declaration between records are relatively fixed by the structure,
Relation between records are relatively fixed by the structure.
ii.
Manager use of query language to solve the problem may
require multiple searches and prove to very time consuming.
Network Data Base
structure:- It builds on the concept of multiple branches, lower level and
higher level structures. A network data base structure views all records in
sets. An owner record and one or more member records.
Relational database
Models: In Relationship data base model, the hierarchical and network
database structures require exploit relationships between records in the data
base. The key terms are used in relational data base model are relations.
Attributes and domains. A relation is
a table with columns and rows.
Key: Key often
referred to the specific structure and components of link list, chain of
pointers (or) a key is a set off one (or) more columns whose combined values
are unique among all occurrences in a given table. There are various types of
relational keys.
i.
Primary key:
A primary key is used to get an unique value.
ii.
Candidate key:
One or more columns whose combined values are unique among all occurrences
iii.
Alternate key:
Any table is simply those candidate keys which are not currently selected as a
primary key.
Note: An alternate key is a function of
all candidate key – primary key.
iv.
Secondary key:
These keys are used to optimize the data access.
INFORMATION TECHNOLOGY
Explain Data Base
Models:-
1.
Distributed data
base:- Sometimes an organisation may require decentralizing its data base
by scattering it with computing resources to several locations, so that the
processing is done at more than sight.
2.
Replicated data
base:- Duplicates of data are provided to the sights, so that we can access
same data concurrently. Replication data base is costly in terms of system
resources and also maintaining the consistency of the data elements.
3.
Partitioned data
base:- Database is divided into parts that are required and appropriate for
the respective sight, only those sights are partitioned or distributed without
replication of entire data.
4.
Entity
relationship model data base:- ER model is a specialized graphic that
illustrates relationship between entities in the data base. It is used to
produce a type of conceptual scheme of a system asset of all entities of same
time is called “entity set”. The degree of relationship indicates the link
between two entities for specific occurrence of each. The degree of
relationship is called “cardinality”. The basics of “ER” diagram are
Define object
oriented data base:- Objects are entities converging some meaning for us
and possess such retributes to characterize them and interacting with each
other. Object oriented data base provides mechanism to store complex such as
images audio and video.
Any object in the real world consists of member data and
member functions. So each object is an independently functioning application.
Examples of object
oriented language:-Pipthonog, C++, JAVA, C#, Small talk etc.
Client-server data
base:-In client server data base where client requests the server and
server response according to the client request. Client machine contains user
interface, server machine contains data base, both are coupled with a network
of highbandwidth.
Client 1
Client 2 
Client-Server Data Base
Server
The above diagram is an example of two tier architecture.
Knowledge Data Base:-
A knowledge Data Base System provides system provides functions to define, create, modify, delete and
read data in a system. The time data maintained in a data base system
historically has been declarative data description the static aspects of the
real world objects and their associations. In this knowledge data base, dynamic
aspects of the real world objects are stored; so that it can be used for
decision support system and executive information system it contains integrated
data. Detailed data, summarized data, historical data and meta data is called a
“DATA WAREHOUSE” The process of recognizing the required data among data ware
house “DATA MINING”
Explain the
components of Data Base:- There are 2 components used in data base
1.
Data definition Language (DDL)
2.
Data Manipulation Language (DML)
Data Definition
Language:- It defines the conceptual level which means it is in between
“user level” and “physical level”
Functions of data
definition language:-
1.
It describes schema and sub-schema
2.
They indicates the keys of the record
3.
Provide data security
4.
Provide logical and physical data independence
DATA MANIPULATION
LANGUAGE:- They provide data manipulation techniques like deletion,
modification, insertion, replacement, retrieval, sorting and display of data.
They facilitates use of relationship between records they provide for
independence of programming languages by supporting several high level
procedural languages like PL/SQL,COBAL, C++ … etc
STRUCTURE OF DBMS:-
DDL COMPILER:-
1.
It converts data definition statements into set of
tables.
2.
Tables contain meta-data
DATA MANAGER:-
1.
It is a central software component
2.
It refers to by data base control system
3.
It converts operations in user queries to physical file
system
FILE MANAGER:-
1.
Responsible for file structure
2.
Responsible for managing space
3.
Responsible for requesting block from disk manager
4.
Responsible for transmitting required records to data
manager.
DISK MANAGER:-
1.
It is a part of operating system it carries out all
physical input, output operations.
PUENY MANAGER:-
2.
It interprets users query.
3.
It converts to an efficient series of operations
4.
It uses information to modify query
5.
It uses data dictionary
6.
It prepares an optimal plan to access data base for
efficient data retrieval
DATA DICTIONARY:- It
maintains information of meta-data and data
DATA BASE
ADMINISTRATOR (DBA):-
Data Base Administration (DBA) is a person responsible for
the design, implementation, maintenance and repair of an organizations data
base. They are also known as coordinator (or) “data base programmer”. The
following are the roles and responsibilities of data base administrator.
1.
DBA has an overall authority to establish and control
data definitions and standards.
2.
DBA provides data base security system to restrict
un-authorised users.
3.
DBA also trains and assists application programmes in
the use of data base.
4.
Data base administrator must have a discussion with
users and then he decides the schedule and accuracy requirements, the way and
frequency data access, search strategies, physical storage response time, level
of security etc.
5.
DBA is responsible for originating and updating of
data.
6.
DBA is responsible for controlling access to data base and two other
important functions that handled by the DBA using DDL.
7.
DBA prepares “documentation” which includes procedures,
guidelines, data description and data base environment.
8.
DBA is responsible for taking back ops and recovery
procedures.
9.
DBA also monitors the data base environment.
10. DBA
also setup procedures for identify and correcting violation of standards,
documents and correct errors. Finally DBA is responsible for creating new
utility programmes (or) new system releases.
TYPES OF DATA BASES:-
The growth of distributed processing, end user computing,
decision support and executive info-systems has caused the development of
several types of data bases.
OPERATIONAL DATA
BASE:- These data bases store detailed data needed to support support the
operation of the entire organisation. Ex: customer data base, personnel data
base, inventory database etc.
MANAGEMENT DATA BASE:-
These data bases store data and info extracted from selected operational and
external data base. It consists of summarized data and information to support
managerial decision making.
INFORMATION WARE DATA
BASE:- In his data base, current and previous years of data is stored it is
an external source of data that has been standardized and integrated so that it
can be used by managers and end users.
EXTERNAL DATA BASE:-
Privately owned online data bases. Ex: databanks, newspapers magazines and
other periodicals from bibliographic data base.
TEXT DATA BASE:-
IT has stored data documents electronically, they use text data base management
system software to help, create, store, search retrieve, modify and assemble
documents and other information stored as text data in such data bases.
IMAGE DATA BASE:-
Wide variety of images are stored electronically. Ex: photographs, animated
videos etc.,
STRUCTURED QUERY
LANGUAGE:- A query language is a set of commands to create, update and
access data from a data base allowing user to raise queries with the help of
the programmers.
Ex: My SQL server, oracle data base.
SQL usually consists of 3 parts
Ø
DML-DATA MANIPULATION LANGUAGE
Ø
DDL-DATA DEFINITION LANGUAGE
Ø
DCL-DATA CONTROL LANGUAGE
DML – It consists
of select, update, delete, insert statements
DDL – CREATE
& ALTER
DCL – GRANT &
REVOKE
BACK UPS:- This
is an utility programme used to copy the entire content of the data base
(duplication of data) it consists of root file log file mirror log file and
other data base files called db data base spaces.
RECOVERY:-
Recovery is the sequence of tasks performed to restore a data base to some
point in kind recovery is performed when hardware (or) media failure occurs.
Backup is a good practice of recovery.
ONLINE BACK UP:-
Online backup process being the data base engine externalizes all cached data
pages kept in memory to the data base files on disk the process is called a
check point.
TRANSACTION LOG:-
DATA BASE engine continues recording activity in the transaction log file while
the data base is being back up.
LIVE BACK UP:-
This provides a redundant copy of the transaction log for restart your system
on a secondary machine in the event the primary data base becomes unusual.
OFFLINE BACK UP:
Back up is being when the data base is shutdown through a normal shutdown
process. The database engine commits the data in the data base files.
STRATEGY FOR
DEVELOPING A BACKUP & RECOVERY:-
Ø
Understand the backup & recovery means to
your business
Ø
Commits time & source for the project
Ø
Beware of any external factor that affect the
recovery
Ø
Develop test, time, health check, deploy &
monitor
DATA WARE HOUSE:-
A data ware house is a repository of an organizations
electronically stored data ware houses are designed to facilitate reporting and
supporting data analysis.
ADVANTAGES:
i.
Reduces the response time
ii.
Optimises the reporting and analysis the information
iii.
Reports in operation system often required written
specific computer programmes which was slow and expensive (disadvantage)
separate data bases being to support management information and analysis
process this we use different tools such as spread sheet so that the
requirement of managers auditors and accountants will get very easy and fast
data to analyse. Data ware houses have evolved through several fundamental
stages.
OFFLINE OPERATIONAL
DATA BASE:- In this initial stage are developed by simply copying the data
base of an operational system to an offline server where the processing load of
reporting does not impact on the operational system performance.
OFFLINE DATAWARE
HOUSE:- In this stage of evolution are updated on a regular time cycle
(usually, daily weekly or monthly)
REAL TIME DATA WARE
HOUSE:- At this stage updation takes place in transaction base.
Ex:- Delivery of goods and ticket booking
INTEGRATED DATA WARE
HOUSE:- At this stage transactions that are passed back into the operation
system for use in daily activity of the organisation.
COMPONENTS OF DATA
BASE HOUSE:- The primary components of the data ware house are
i.
DATA SOURCES:- Where
data is stored electronically where management can use the data for analysis
(or) analytics for server IBM DB2 etc for client side oracle DB-Informix etc.
ii.
DATA TRANSFORM:-
In this layer receives data from data sources cleans and standardize the data.
This is often called “staging”.
iii.
META DATA:-
In few data ware houses these are optional components such as dependent data
marts, logical data marts, operational data store.
ADVANTAGES OF DATA
WARE HOUSE:-
i.
It increases the ability of access to reports and
analysis of information.
ii.
Increases data consistency.
iii.
Able to combine data from different sources.
DISADVANTAGES:-
i.
Extracting cleaning and loading data could be time
consulting
ii.
We can get out dated information quickly
iii.
Providing training to end users
iv.
Data warehouse is usually a non static and maintenance
costs are high.
MINING: Mining is
concerned with the analysis of data and picking out relevant information it is
computer which is responsible for finding the patterns by identifying the
underlying roles and features in the data.
Examples of data mining software’s are SPSS, SAS, think
analysis and G-stat these are the following stages where we can interpret and
evaluation takes place.
i.
Selection: We have to take the data
according to some criteria.
ii.
Pre-processing: At this stage
certain information is removed which is deemed unnecessary and may slow down
queries.
iii.
Transformation:- The data is
transformed into different software tools like demographic so that it is easily
navigable.
iv.
Interpretation & evaluation:-
These patterns are identified by the system and transpose into knowledge which
is used to support human decision making.
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