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Database management systems
asked Dec 6, 2015 in Computer Science - IT by durgaprasadk | 10,141 views

2 Answers

+1 vote

1.Manages Information
Eg: A system may have to maintain information of various employees working in its organization, their names,addresses, and other details which may in later instance be modified or deleted.

2.Easy to operate on data
Inserting more data, deleting unuseful data, updating, searching etc is easy.

Let me give you a situation to understand this,suppose you are initiating a transaction wherein you have to transfer Rs 50 from Account A to B. Say account A contains Rs 300 and B contains Rs 200. You will execute the transaction in 2 steps. 1st subtract rs 50 from A and 2nd Add 50 to B. Now the database will reflect updated values A= 250 and B=250

Now imagine ,there occurs a system failure after 1st step of transaction. the database will reflect A=250 and B=200. that means rs 50 is destroyed by the system. This inconsistency is prevented by database approach. Either all changes are reflected (ie. A=250 and B=250) or none are (ie. A=300 and B=200).

4. Persistent
Once your transaction has completed successfully ( we say the transaction is committed), data will remain persistent,  ie. it will not be lost or deleted until you do it manually.

5. Security of Data
Only authorized users are allowed to access the data.

6. Self describing Nature
DBMS contains data as well as data definition (stored in system catalog). In File Processing System data definition is a part of Application Programs.

7. Isolation between programs and data
As mentioned above, data definition is stored in catalog ( Not in programs). Hence, User doesn't need to make changes in programs if he changes the structure of the data.

8. Supports multiple views
Different users may have interest in different groups of data. User is allowed to view the data in which he is interested.
EG. one user is only interested for student mark list,other user is interested for courses attended by that student, these multi-user views are satisfied by DBMS

answered Dec 7, 2015 by Sonal
point 3 : consistency management,how is that managed in SQLSERVER 2005 ?
–2 votes
There are a number of characteristics that distinguish the database approach with the file-based approach.

Self-Describing Nature of a Database System

A Database System contains not only the database itself but also the descriptions of data structure and constraints (meta-data). This information is used by the DBMS software or database users if needed. This separation makes a database system totally different from the traditional file-based system in which the data definition is a part of application programs.

Insulation between Program and Data

In the file based system, the structure of the data files is defined in the application programs so if a user wants to change the structure of a file, all the programs that access that file might need to be changed as well. On the other hand, in the database approach, the data structure is stored in the system catalog not in the programs.  Therefore, one change is all that’s needed.

Support multiple views of data

A view is a subset of the database which is defined and dedicated for particular users of the system. Multiple users in the system might have different views of the system. Each view might contain only the data of interest to a user or a group of users.

Sharing of data and Multiuser system

A multiuser database system must allow multiple users access to the database at the same time. As a result, the multiuser DBMS must have concurrency control strategies to ensure several users  access to the same data item at the same time, and to do so in a manner  that the data will always be correct – data integrity.

Control Data Redundancy

In the Database approach, ideally each data item is stored in only one place in the database.  In some cases redundancy still exists so as to improve system performance, but such redundancy is controlled and kept to minimum.

Data Sharing

The integration of the whole data in an organization leads to the ability to produce more information from a given amount of data.

Enforcing Integrity Constraints

DBMSs should provide capabilities to define and enforce certain constraints such as data type, data uniqueness, etc.

Restricting Unauthorised Access

Not all users of the system have the same accessing privileges.  DBMSs should provide a security subsystem to create and control the user accounts.

Data Independence

System data (Meta Data) descriptions are separated from the application programs.  Changes to the data structure is handled by the DBMS and not embedded in the program.

Transaction Processing

The DBMS must include concurrency control subsystems to ensure that several users trying to update the same data do so in a controlled manner.  The results of any updates to the database must maintain consistency and validity.

Providing multiple views of data

A view may be a subset of the database. Various users may have different views of the database itself.  Users may not need to be aware of how and where the data they refer to is stored.

Providing backup and recovery facilities

If the computer system fails in the middle of a complex update process, the recovery subsystem is responsible for making sure that the database is restored to the stage it was in before the process started executing.

Managing information

Managing information means taking care of it so that it works for us, and is useful for the work we are doing. The information we collect is no longer subject to “accidental disorganization” and becomes more easily accessible and integrated with the rest of our work. Managing information using a database allows us to become strategic users of the data we have.

We often need to access and re-sort data for various uses. These may include:

Creating mailing lists
Writing management reports
Generating lists of selected news stories
Identifying various client needs
The processing power of a database allows it to manipulate the data it houses, so it can

Skip fields
So a database tracks data, finding the bits you need and processing them in the way you arrange for them to be processed.

Because of the versatility of databases, we find them powering all sorts of projects. A database can be linked t
answered Dec 6, 2015 by durgaprasadk
Copied content from site : http://opentextbc.ca/dbdesign/chapter/chapter-3-characteristics-and-benefits-of-a-database/ should have proper reference links .
Please be specific on questions so that answers are simple ..If contents are copy paste kindly add links ...also your answer is not complete !