In
this session, we will get to know what a database is and why those are that
important. I strongly recommend going through my previous post 'Introduction-to-database-1' to understand this session with
ease.
From
the last session, we know what data is. Now let us consider we have a lot of
data consisting of the details of the employees in an organization. As such
data is really important for an organization; it needs to be stored somewhere
and somehow. It is sure that maintaining hard copy of those is not only tedious
but also it is not very easy to search anything from those. Hence it is clear
that we need to store them as softcopy.
Now
it’s time for us to discuss on the ways of storing our data as softcopy. One
can say that we can store them as they are in flat files where data is stored
in a plain text file. Each line of the text file holds one record (We will get
to know what a record is soon), with fields separated by delimiters, such as
commas or tabs. Though maintaining data in flat files is simple in structure,
they don't have multiple tables (Data is stored in the form as tables in a
database). Also, data cannot be viewed or retrieved easily and quickly when the
amount of data maintained grows in size over a period of time. There are many
other disadvantages of
maintaining data in flat files such as:
1) Detection of duplicate record is not that easy.
2) Duplication of records is possible.
3) Data retrieval is almost impossible when the data
grows in size.
4) Data entered may not be of same data type when
entered by different persons. For example, one person may enter the salary of
an employee as 5000 while some other may enter it as 5K.
5) Security of these systems is quite less.
These are only few reasons for change in the method
to store data from flat file database system to Relational database systems.
DATABASE:
Database is an organized collection of data so that
data retrieval as well as operations on the data can be done easily. Data is
stored in the form of tables in a database. A database table is similar to any
Microsoft excel sheet that has rows and columns. The data in a column should be
of same data type (We will get to know data types in the next session).
Record:
A record is the data arranged in a row such that the data in a row gives
information of particular entity.
Databases are generally represented by the following symbol, so if you come across this symbol anywhere,its nothing but a database.
Why data bases?
1) Data retrieval or updating becomes easy as the data can be queried.
2) Multiprocessing and multi-threaded are supported.
3) Quality in data as many constraints can be imposed on the data being
entered.
4) Data type mismatch in the columns can be eliminated completely.
5) Reliable
6) Transactions can be handled by databases.
7) Data integrity
8) Access through networks is made possible by databases.
9) Due to indexing, records for
particular condition are fetched easily.
These are only few advantages we have with the
databases.
Some of the databases and their vendors are as
follows:
1)
Oracle
Corporation – Oracle Database 11g (Proprietary)
MySQL (GPL
or Proprietary)
2)
Sybase
–Adaptive Database Server;
SQL Anywhere (Proprietary)
3)
IBM
– DB2, Informix Dynamic Server (Proprietary)
4)
FileMaker
– FileMaker (Proprietary)
5)
Microsoft
– SQL Server, Access
6)
Hewlett-Packard
– HP NonStop SQL (Proprietary)
7)
Apache – Apache Derby (Apache License)
8)
PostgreSQL
Global Development Group – PostgreSQL (PostgreSQL open
source license)
NOTE:
All
the above databases except the Microsoft products are compatible with at least
one more operating system apart from Microsoft Windows.
