3. The following are the basic terminology related to data organization:
1. Data: Data is a single piece of information. Data refers to collection of facts usually collected as the
result of experience , observation or experiment, or processes within a computer system, or a set of
premises. Data may consist of number , words, or images, particularly as measurements or
observations of a set of variables. Data is often viewed as a lowest level of abstraction from which
information and knowledge are derived.
2. Data Item: A data item refers to a single unit of values. For example, telephone number, student
name, Date of birth, age, and address, aggregate marks in each semester of examination are data
items. Data items that can be divided into sub-items are called groups items whereas those item
which cannot be divided into sub-items are called elementary items. For example, address is a group
item as it is usually divided into sub-items such as house number, street no, city , pin code etc. While
Roll no, marks, city ,pin-code are normally treated as elementary items.
3. Entity: an entity is something that has certain attributes or properties which may be assigned
values. The values assigned may be either numeric or non-numeric. For example, a student is an
entity. The possible attributes for a student can be roll no, name, date of birth, sex etc.
4. Entity Set: An entity set is a collection of similar entities. For example, student of a class, employees
of an organization, product manufacturing unit etc. from an entity set.
4. Roll No. Name Sex
1119 Mr. X Male
5. Record: A record is one complete set of fields or related fields for a particular event. For
example,
6. File: A file is a collection of related records. For example, a file containing records of all
students in a class, a file containing records of all employees of organization.
7. Key: A key is a data item in a record that makes unique values and can be used to distinguish
a record from other records. Various keys are there, primary key, foreign key, composite key,
and alternate key. These topics are related with database management system (DBMS).
8. Information: The terms data and information have been used to mean same thing. But
actually information is more that just data. In simple terms, information is a processed data.
Data is just a collection of values (raw data), from which no conclusion can be drawn. Thus
data as such is not useful for decision making. When the data is processed by applying certain
rules, new generated data becomes information.
5. Data Organization Issues
Some of the data organization issues are as follows:
1. Data Redundancy: Data redundancy means same information is duplicated in several files.
This makes data redundancy. Data redundancy occurs when the same piece of data is
stored in two or more separate places and is a common occurrence in many businesses.
Data redundancy can be found in a database, which is an organized collection of
structured data that’s stored by a computer system or the cloud. A retailer may have
database to track the products they stock. If the same product gets entered twice by
mistake, data redundancy takes place.
2. Data Inconsistency: Data inconsistency means different copies of the same data are not
matching. That means different versions of same basic data are existing. This occurs as the
result of update operations that are not updating the same data stored at different
places. For example, Address Information of a customer is recorded differently in different
files.
6. 3. Difficulty in Accessing Data: It is not easy to retrieve information using a conventional
file processing system. Convenient and efficient information retrieval is almost impossible using
conventional file processing system.
4. Data Isolation: Data are scattered in various files and the files may be in different format, writing
new application program to retrieve data is difficult.
5. Integrity Problems: The data value may need to satisfy some integrity constraints. For example the
balance field Value must be greater than 5000. We have to handle this through program code in file
processing systems. But in database we can declare the integrity constraints along with definition
itself.
6. Atomicity Problem: It is difficult to ensure atomicity in file processing system. For example,
transferring Rs 100 from account A to account B. If a failure occurs during execution there could be
situation like Rs 100 is deducted from Account A and not credited in Account B.
7. Concurrent Access anomalies: If multiple users are updating the same data simultaneously it will
result in inconsistent data state. In file processing system it is very difficult to handle this using
program code. This result in concurrent access anomalies.
8. Security Problems: Enforcing security constraints in file processing system is very difficult as the
application programs are added to system in an ad-hoc manner.
8. What is Database
File System vs DBMS
- Operating System in Laptop – in built File System (NFS) – Folders and Sub folders , hierarchical
system
DBMS – Client Server Architecture – Database in Centralized location, users everywhere,
role based access control, no data location –it is independent
Attribute –Meta data – data about data ex c://Folder1/Folder
Structured Data – RDBMS
Unstructured Data – Hadoop/Big Data
10. Database is an organized collection of data , so that software program can quickly and easily access
the needed data , multiple users can share for various purposes
A collection of information that is grouped and stored in structured way is called ‘database’
The database is created and maintained by an integrated set of programs termed “ Database
Management Systems (DBMS)
DBMS is a software tool used to perform various types of operations on data in a database , helps in
efficient and convenient use of database by utilizing and maintaining huge collection of data
Ex Oracle , Ingress ,MySQL , Sybase etc.
Database & DBMS Concepts
13. DBMS vs RDBMS
DBMS Data in hierarchical form
RDBMS Data in Tables Tables are related to each other
Every DBMS is RDMBS – No . Since data can be in hierarchical form
Every RDBMS is DBMS –Yes
Tables – Rows and Columns
Rows –Records
Columns – Fields (Attributes –Qualitative )
Each table has relationship with other table
18. Capabilities of DBMS
1.Transaction Management –update ,delete ,modify set of records
2. Concurrency Control –allow concurrency while maintaining consistency of shared data
3. Recovery Management-database returns to consistent state after transaction
fails/aborts
4.Security Management- protection of data against unauthorized access
5.Language Interface-data manipulation using data manipulation commands
6.Storage Management-schema for permanent storage of data
59. Types of Database Systems
1. Active Database: An active database is governed by an event-driven
architecture. Such a system can respond to both external and internal
condition to the database. Such database are mainly used for
statistics gathering, monitoring, authorizing and alerting.
2. Cloud Database: The database that relies on cloud technology is
cloud database. The database and a great portion of the DBMS are
situated in the cloud remotely. To develop the applications for the
database the programmers use web browsers to open APIs. The
same are used by the users to utilize the database.
3. Centralized Database System: In a centralized database system,
there is a single processor along with the peripherals and the storage
devices. The whole database system is physically located at a single
point. The users located at the site are able to get data processing
services from the system. The system also offers services to users
who are located at geographically distant places. They are able to
access it with the help of remote terminals.
60. 4. Parallel Database System: In a parallel database the performance is
improved by the parallelization of various operations such as evaluating
queries, loading data and building indexes. There are multiple disks and
processors in parallel databases. This increases the speed of input/output
and processing. Such applications cannot be efficiently handled by client-
server or centralized databases as they are not powerful enough. In serial
processing the steps are carried out one after another, whereas, in parallel
processing multiple steps are carried out simultaneously.
In a parallel database system a number of microprocessors are connected
using a high speed internet connection. It is necessary to use both processing
parallelism and I/O parallelism so the adequate support can be provided for
inter and intra-transaction parallelism.
5. Client/Server Database System: In order to deal with those environments
where a large number of workstations, PCs, web services, printers, file
servers and other devices are connected using network, the client/server
architecture was designed. The prima idea was to assign certain tasks to
specific servers that have some specialized capability.
6. Distributing Database System: When a database has many parts and the
parts stored in different computers then it said to be a distributed database.
With the help of a distributed database system it is possible to create and
maintain distributed database.
61. 7. Data Warehouse: The task of reporting and data analysis can be
carried out with the help of a special database called data warehouse.
Data from multiple separated sources are integrated together and
stored in the central repository. Both current and historical data are
stored in the data warehouse. These can be used for creating
quarterly or annual reports for the senior management.
8. Data Mining: The process of data mining involves data analysis from
various perspectives and the making a summery from it, which
contains only useful information. Such information can then be used
by the management to cut cost, increase revenue or do both. Data
mining can also be used to find patterns or correlations among a
number of fields that are found in huge database.
9. Spatial Database: Using a spatial database it is possible to store and
query data about objects which includes points, space, polygons and
lines. In a spatial database data acting as real models are spatially
referenced and stored. So, to process spatial data
types databases are required additional functionalities. This is
because they are different from general database that process
different types of characters and numeric data types only
62. 10.Multimedia Database: Apart from supporting the functionalities of the
traditional database system like data
independence, data organization and access, database creation, data
retrieval and data modeling, there must be support for multimedia
data types in a Multimedia Database Management System
(MMDBMS). There has been notable growth in the application of such
database due to the rapid advancement in network technology.
Recently the exchange of multimedia information has also grown
rapidly.
11. Mobile Database: A database that cab be connected with the help of
a mobile device via a mobile network is called a mobile database. The
server and client are connected wirelessly. In order to preserve data
during the connection failure a cache is present to hold data and
transactions the occur frequently. Information is organized in a
structured way using database. For example, distance travelled, list of
contacts or price of articles.
