Advantages of database management system

Advantages of database managementsystem
ASSIGNMENT

Advantages of Database Management System:
The DBMS has a number of advantages as compared to traditional computer
file processing approach. The DBA must keep in mind these benefits or
capabilities during designing databases, coordinating and monitoring the
DBMS.
The major advantages of DBMS are described below:
1. Controlling Data Redundancy:
In non-database systems (traditional computer file processing), each application
program has its own files. In this case, the duplicated copies of the same data
are created at many places. In DBMS, all the data of an organization is
integrated into a single database. The data is recorded at only one place in the
database and it is not duplicated. For example, the dean's faculty file and the
faculty payroll file contain several items that are identical. When they are
converted into database, the data is integrated into a single database so that
multiple copies of the same data are reduced to-single copy.
In DBMS, the data redundancy can be controlled or reduced but is not removed
completely. Sometimes, it is necessary to create duplicate copies of the same
data items in order to relate tables with each other.
By controlling the data redundancy, you can save storage space. Similarly, it is
useful for retrieving data from database using queries.
2. Data Consistency:
By controlling the data redundancy, the data consistency is obtained. If a data
item appears only once, any update to its value has to be performed only once
and the updated value (new value of item) is immediately available to all users.
If the DBMS has reduced redundancy to a minimum level, the database system
enforces consistency. It means that when a data item appears more than once in
the database and is updated, the DBMS automatically updates each occurrence
of a data item in the database.

3. Data Sharing:
In DBMS, data can be shared by authorized users of the organization. The DBA
manages the data and gives rights to users to access the data. Many users can be
authorized to access the same set of information simultaneously. The remote
users can also share same data. Similarly, the data of same database can be
shared between different application programs.
4. Data Integration:
In DBMS, data in database is stored in tables. A single database contains
multiple tables and relationships can be created between tables (or associated
data entities). This makes easy to retrieve and update data.
5. Integrity Constraints:
Integrity constraints or consistency rules can be applied to database so that the
correct data can be entered into database. The constraints may be applied to data
item within a single record or they may be applied to relationships between
records.
Examples:
The examples of integrity constraints are:
(i) 'Issue Date' in a library system cannot be later than the corresponding 'Return
Date' of a book.
(ii) Maximum obtained marks in a subject cannot exceed 100.
There are also some standard constraints that are intrinsic in most of the
DBMSs. These are;
Constraint Name Description
PRIMARY KEY Designates a column or combination of columns as Primary Key and
therefore, values of columns cannot be repeated or left blank.
FOREIGN KEY Relates one table with another table.
UNIQUE Specifies that values of a column or combination of columns cannot
be repeated.

NOT NULL Specifies that a column cannot contain empty values.
CHECK Specifies a condition which each row of a table must satisfy.
Most of the DBMSs provide the facility for applying the integrity constraints.
The integrity constraints are automatically checked at the time of data entry or
when the record is updated. If the data entry operator (end-user) violates an
integrity constraint, the data is not inserted or updated into the database and a
message is displayed by the system. For example, when you draw amount from
the bank through ATM card, then your account balance is compared with the
amount you are drawing. If the amount in your account balance is less than the
amount you want to draw, then a message is displayed on the screen to inform
you about your account balance.
6. Data Security:
Data security is the protection of the database from unauthorized users. Only
the authorized persons are allowed to access the database. Some of the users
may be allowed to access only a part of database i.e., the data that is related to
them or related to their department. Mostly, the DBA or head of a department
can access all the data in the database. Some users may be permitted only to
retrieve data, whereas others are allowed to retrieve as well as to update data.
The database access is controlled by the DBA. He creates the accounts of users
and gives rights to access the database. Typically, users or group of users are
given usernames protected by passwords.
For example,
If you have an account of e-mail in the "hotmail.com" (a popular website), then
you have to give your correct username and password to access your account of
e-mail. Similarly, when you insert your ATM card into the Auto Teller Machine
(ATM) in a bank, the machine reads your ID number printed on the card and
then asks you to enter your pin code (or password). In this way, you can access
your account.

7. Data Atomicity:
A transaction in commercial databases is referred to as atomic unit of work. For
example, when you purchase something from a point of sale (POS) terminal, a
number of tasks are performed such as;
 Company stock is updated.
 Amount is added in company's account.
 Sales person's commission increases etc.
All these tasks collectively are called an atomic unit of work or transaction.
These tasks must be completed in all; otherwise partially completed tasks are
rolled back. Thus through DBMS, it is ensured that only consistent data exists
within the database.
8. Database Access Language:
Most of the DBMSs provide SQL as standard database access language. It is
used to access data from multiple tables of a database.
9. Development of Application:
The cost and time for developing new applications is also reduced. The DBMS
provides tools that can be used to develop application programs. For example,
some wizards are available to generate Forms and Reports. Stored procedures
(stored on server side) also reduce the size of application programs.
10. Creating Forms:
Form is very important object of DBMS. You can create Forms very easily and
quickly in DBMS, once a Form is created, it can be used many times and it can
be modified very easily. The created Forms are also saved along with database
and behave like a software component.
A Form provides very easy way (user-friendly interface) to enter data into
database, edit data, and display data from database. The non-technical users can
also perform various operations on databases through Forms without going into
the technical details of a database.

11. Report Writers:
Most of the DBMSs provide the report writer tools used to create reports. The
users can create reports very easily and quickly. Once a report is created, it can
be used many times and it can be modified very easily. The created reports are
also saved along with database and behave like a software component.
12. Control over Concurrency:
In a computer file-based system, if two users are allowed to access data
simultaneously, it is possible that they will interfere with each other. For
example, if both users attempt to perform update operation on the same record,
then one may overwrite the values recorded by the other. Most DBMSs have
sub-systems to control the concurrency so that transactions are always recorded"
with accuracy.
13. Backup and Recovery Procedures:
In a computer file-based system, the user creates the backup of data regularly to
protect the valuable data from damaging due to failures to the computer system
or application program. It is a time consuming method, if volume of data is
large. Most of the DBMSs provide the 'backup and recovery' sub-systems that
automatically create the backup of data and restore data if required. For
example, if the computer system fails in the middle (or end) of an update
operation of the program, the recovery sub-system is responsible for making
sure that the database is restored to the state it was in before the program started
executing.
14. Data Independence:
The separation of data structure of database from the application program that
is used to access data from database is called data independence. In DBMS,
database and application programs are separated from each other. The DBMS
sits in between them. You can easily change the structure of database without
modifying the application program. For example you can modify the size or
data type of a data items (fields of a database table).

On the other hand, in computer file-based system, the structure of data items are
built into the individual application programs. Thus the data is dependent on the
data file and vice versa.
15. Advanced Capabilities:
DBMS also provides advance capabilities for online access and reporting of
data through Internet. Today, most of the database systems are online. The
database technology is used in conjunction with Internet technology to access
data on the web servers.

Advantages of database management system

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