INTRODUCTION TO DATABASE-2

            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.