Introduction of database system :
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| DBMS |
What is Database management system, or simply DBMS..?
Just, consider the phonebook of your mobile phone. It
contains a list of all contacts. In general, this list includes contact names
and numbers. But, it can also include some other data about contacts, such as
address, birth-date, e-mail id, etc depending upon the features of your mobile.
You can insert (store) new contact details in this phonebook, update (modify)
existing contact details, delete (remove) some contacts if not required, or
search for a particular contact. This phonebook has a database, collection of
data about various contacts, and a set of programs, to perform various
operations like as insert, update, delete and search. In short, the phonebook
of your mobile phone is one kind of DBMS.
Assembly language programming
This post provides an overview of database management system,
formerly known as DBMS. Chapter begins with the description about basic
concepts of database management systems such as data, information, database,
and database systems. After this, various ways to store and manage data are
described including paper based systems, file processing systems and database
management systems with their advantages and disadvantages. This follows the
overview of various terminology used in DBMS. This includes data administrator,
database administrator, metadata, system catalog, data dictionary and data
warehouse.
How to computer work and use?
DBMS – an overview
This section start with the description about data and
information. It differentiates data and information – almost synonymously used
terms in practice, but technically totally different from one another. After
this, database and database systems are defined along with primary goals of
DBMS. It follows description of operations that can be performed on DBMS and
some of the well-known database-system applications.
What is database?
“A database is a collection
inter-related data.”
It represents some aspect of the real world.
For example, consider a collection of customer id, name,
address, contact number for some customer of a bank. Here, all the data – id,
name, address, contact number – are inter-related. They all belong to some
particular customer. In other words, they represent some particular customer.
Also, data about accounts, loans, employees, branches are
inter-related in context of some banking system. So, these data, in combine,
forms a database for a bank.
A database is some kind of collection of data. Though, any
arbitrary (or random) collection of data is not considered as a database. For
example, collection of some vehicle number, balance of account and percentage
of student do not form a database.
Database management system
“A management system may be a collection of inter-related data and a group of programs to control those data.”
Data manipulation involves various operations like store
data, modify data, remove data and retrieve data.
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| DBMS |
In other words, DBMS can be described as-
DBMS = Database + A set of Programs
Where database is referred as DB and a set of programs are
referred as MS (Management System).
Database management system is also referred as database
system only.
Notice here that, the database and software (a set of
programs) together is called database system.
The primary goal of a DBMS is to provide efficiency and
convenience in storing and retrieving database information.
DBMS also provides safety of the information against system
crashes as well as an unauthorized access.
Operations performed on Database Systems
A database system can be considered as a container to store
database. It also provides functionalities to manipulate database.
Various operations can be performed on such kind of database
systems. Some of the basic operations are :
Creating containers for database such as tables, or files.
Inserting new data into existing database.
Modifying (or updating) data in existing database.
Removing (or updating) data from existing database.
Retrieving data from existing database.
Destroying containers for database such as tables, or files.
Along with these, a number of different operations can be
performed on database systems depending upon the requirements of the system.
These operations may include database back-up and recovery, performance
monitoring, authorizing data access to provide safety to the database, and so
on.
Basic knowledge of Computer/Computer knowledge
Database system Applications
Now a day, DBMS are used in number of applications. Some of
the well-known applications are listed in table given in
System Data/Information
to be managed
Banking system Customers,
Accounts, Loans, Employees, Transactions…
Inventory system Items,
Bills, Orders, Customers, Vendors, Employees….
Library system Books,
Magazines, Authors, Publications, Students, staff, Faculties…
Railway
reservation system Train, Routes,
Fairs, Schedules, Stations, Passengers, Reservations, Employees….
College/university Students, Subjects,
Staff, Results, Scholarships…
Hospital
management system Patients, Doctors,
Medicines, Employees, Wards, Instrument, Beds…
Cyber-Café
management Customers,
Computers, Plans, Employees, Bills, Usages….
System
Data v/s
Information
Data is plural form
of ‘datum’. Data and information are generally represented in form of
collection of
characters- digits
and alphabets. But, in the world of computers, they can be in form of images, sounds,
or even videos.
Data
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Information
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Data means known facts,
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Information
means processed or organized data.
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Examples:
Student
no: 7047
Student
name: “raj”
City name:
”vadnagar”
Account
number: “A01”
Balance:
10000
|
Examples:
Percentage
: 84.66%
Run-rate
in cricket match: 6.0 runs/over
|
Data convey
something less, comparatively.
It is not
convenient to represent result as marks of 5 subjects in form of -95, 56, 75,
90, 86.
|
Information
conveys something more, comparatively.
It is
convenient to represent result as a percentage in form of 84.66%
|
Data are
row materials used to derive information
For
example, masks of subjects.
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Information
is a product derived from data
For
example, percentage.
|
Though, data
and information are technically different form one-another, they are used
synonymously in general practice and so, in this book also, they are used inter
changeably.
Data
storage: Paper-based v/s Computer-based system
Databases
were right there before the invention of computers, and computer based database
systems. At that time, databases were stored on papers. Still now, size of database
is small, paper-based systems are used to manage it.
Paper-based
systems are very simple to use. They don’t require any computer related skills.
Also, they don’t require any investment in preparing programs, databases, and
installing computers. So, they are cheap too.
But, they
are convenient only when database size is smaller and data stored in database
don not change. They become cumbersome with increase in database size. Some of
the disadvantages of these paper-based systems, in comparison with computer-based
systems, are as follows.
1.
Back-up
It is not possible to take faster and automatic
back-up of database stored in hundreds or thousands of pages. Computer-based
systems make this possible.
2.
Compactness
It is not possible to store data compactly. For
example, to store all words of English Dictionary, hundreds of pages are
required. While in computer based system, only few kilobytes of memory is
required for this purpose.
3.
Data Retrieval
Data retrieval in paper-based systems requires too
much manual effort. But, computer-based systems provide enhanced data retrieval
in easy and efficient way.
4.
Editing
It is almost impossible to edit data written on
papers. Such kind of editing will result in chaos. Computer-based systems do
not suffer from such kind of problems. It is easy to edit any information
stored in computers, in form of file or tables.
5.
Remote Access
It is not possible to access data stored on papers
remotely. So, it becomes must for a user to access data at a location where
these data are kept on papers. In
computer-based systems, it's possible to access data remotely.
6.
Sharing
Sharing of data among multiple users at a same time is not
possible in paper-based systems. Computer-based systems allow such kind of
sharing.
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