What is Database? | How data base work.

 Introduction to Database

A database (DB) is an organized collection of data. More specifically, a database is an electronic system that allows data to be easily accessed, manipulated and updated. In other words, a database is used by an organization as a method of storing, managing and retrieving information. The main purpose of the database is to operate a large amount of information by storing, retrieving, and managing data.

Software programmers are well acquainted with database concepts through relational databases like Oracle, SQL SERVER and MYSQL, etc. Typically, a database structure stores data in a tabular format.

 

Database architecture may be external, internal or conceptual. The external level specifies the way in which every end-user type comprehends the organization of its corresponding relevant data in the database. The internal level deals with the performance, scalability, cost and other operational matters. 

The conceptual level perfectly unifies the different external views into a defined and wholly global view, It consists of every end-user required generic data.

File system:

File System Before the use of a computer, a manual file system was used to maintain the records and files Data were stored and processed using a traditional file system and it makes it easy to find any information In this traditional file system, each file is independent of other file and data in the different fle can be integrated only by writing an individual program for each application. 

The data and application proe that uses the data are arranged that any change to data requires modification of all the programs thate the data. Sometimes, it is not possible to identify all the programs using data and identified one se error basis.

 All functional areas in the organization create, processes its own files.

The files such as inventory and payroll generate separate files and do not communicate with each other.In the file systm, the organization was simple to generate and had better local control but the data of an organization has dispersed throughout the functional sub-system.

How File System Works?

 A file system stores and organizes data and can be thought of as a type of index for all the data contained in a storage device.

 These devices can include hard drives, optical drives and flash drives. File systems specify conventions for naming files, including the maximum number of characters in a name, which characters can be used and, in some systems, how long the file name suffix can be. 

In many file systems, file names are not case sensitive. Along with the file itself, file systems contain information such as the size of the file, as well as its attributes, location and hierarchy in the directory in the metadata.

 Metadata can also identify free blocks of available storage on the drive and how much space is available. A file system also includes a format to specify the path to a file through the structure of directories. 

A file is placed in a directory or a folder in Windows OS or subdirectory at the desired place in the tree structure. 

PC and mobile OS have file systems in which files are placed in a hierarchical tree structure. Before files and directories are created on the storage medium, partitions should be put into place. 

A partition is a region of the hard disk or other storage that the OS manages separately. 

One file system is contained in the primary partition, and some OS allow for multiple partitions on one disk.

 In this situation, if one file system gets corrupted, the data in different partition will be safe.

Disadvantages of File System

File System manages data using files in hard disk. 

Users are allowed to create, delete and update the files according to their requirement. 

Let us consider the example of file based University Management System. Data of students is available to their respective Departments, Academics Section, Result Section, Accounts Section, Hostel Office etc.

 Some of the data is common for all sections like Roll No, Name, Father Name, Address and Phone number of students but some data is available to a particular section only like Hostel allotment number which is a part of hostel office. 

Let us discuss the issues with this system: 

Redundancy of Data:

Data is said to be redundant if same data is copied at many places. If a student wants to change Phone number, he has to get it updated at various sections. Similarly, old records must be deleted from all sections representing that student.

  Inconsistency of Data:

Data is said to be inconsistent if multiple copies of same data does not match with each other. If Phone number is different in Accounts Section and Academics Section, will be inconsistent. Inconsistency may be because of typing errors or not updating all copies of same data.

 Difficult Data Access: 

A user should know the exact location of file to access data, so the process is very cumbersome and tedious. If user wants to search student hostel allotment number of a student from 10000 unsorted students’ records, how difficult it can be.

 Unauthorized Access:

 File system may lead to unauthorized access to data. If a student gets access to file having his marks, he can change it in unauthorized way.

 No Concurrent Access: 

The access of same data by multiple users at same time is known as concurrency. File system does not allow concurrency as data can be accessed by only one user at a time. No Backup and Recovery: File system does not incorporate any backup and recovery of data if a file is lost or corrupted.