1. A database is a software program, used to store, delete, update and retrieve data. A
database can be limited to a single desktop computer or can be stored in large
server machines, like the IBM Mainframe. There are various database management
systems available in the market. Some of them are Sybase, Microsoft SQL Server,
Oracle RDBMS, PostgreSQL, MySQL, etc.
The Advantages of a DBMS
Improved availability: One of the principle advantages of a DBMS is that the
same information can be made available to different users.
Minimized redundancy: The data in a DBMS is more concise because, as a
general rule, the information in it appears just once. This reduces data redundancy,
or in other words, the need to repeat the same data over and over again.
Accuracy: Accurate, consistent, and up-to-date data is a sign of data integrity.
DBMSs foster data integrity because updates and changes to the data only have to
be made in one place. The chances of making a mistake are higher if you are
required to change the same data in several different places than if you only have
to make the change in one place.
Program and file consistency: Using a database management system, file formats
and system programs are standardized. This makes the data files easier to maintain
because the same rules and guidelines apply across all types of data. The level of
consistency across files and programs also makes it easier to manage data when
multiple programmers are involved.
User-friendly: Data is easier to access and manipulate with a DBMS than without
it. In most cases, DBMSs also reduce the reliance of individual users on computer
specialists to meet their data needs.
Improved security: As stated earlier, DBMSs allow multiple users to access the
same data resources. This capability is generally viewed as a benefit, but there are
potential risks for the organization. Some sources of information should be
protected or secured and only viewed by select individuals. Through the use of
passwords, database management systems can be used to restrict data access to
only those who should see it
Warehouse of Information

2. Database management systems are warehouses of information, where large
amounts of data can be stored. The common examples in commercial applications
are inventory data, personnel data, etc. It often happens that a common man uses a
database management system without even realizing it. The best examples would
be the address book of a cell phone, digital diaries, etc. Both these equipment store
data in their internal database.
Systematic Storage
The data is stored in the form of tables. The tables consist of rows and columns.
The primary and secondary key help to eliminate data redundancy, enabling
systematic storage of data.
Changes to Schema
The table schema can be changed and it is not platform dependent. Therefore, the
tables in the system can be edited to add new columns and rows without hampering
the applications that depend on that particular database.
No Language Dependence
Database management systems are not language dependent. Therefore, they can be
used with various languages and on various platforms.
Table Joins
The data in two or more tables can be integrated into a single table. This enables to
reduce the size of the database and helps in easy retrieval of data.
Multiple Simultaneous Usage
The database can be used simultaneously by a number of users. Various users can
retrieve the same data simultaneously. The data in the database can also be
modified based on the privileges assigned to users.
Data Security
Data is the most important asset. Therefore, there is a need for data security.
Database management systems help to keep the data secured.
Privileges
Different privileges can be given to different users. For example, some users can
edit the database, but are not allowed to delete the contents of the database.