Introduction to Database Management Systems
Data:Data is the information that has been translated into a form that is more convenient to process or move.
Database: The collection of related data is termed as Database which is organized in such a way that it can be easily retrieved and managed.
Database Management System:
-A Database Management System (DBMS) is system software which manages the data. It can perform various tasks like creation, retrieval, insertion, modification and deletion of data to manage it in a systematic way as per requirement.
- Database systems are designed to manage large amount of data by providing security from accidental crash of system and unauthorized access. DBMS provides
convenient and efficient environment which used to handle the data.
Purpose of Database Systems:
-Programming languages like Java, .Net are used to develop customized software's. Every software or application has its data to be stored permanently.
-Programming languages cannot store data permanently. For this purpose we have to use the Database Management System. The DBMS plays a significant role in storing and managing data.
-In an application we store data in DBMS and for operations like insertion, modification or deletion we write code in programming languages i.e. software is usually created with the help of both Programming language and Database.
-When the application is executed on client side, the client or user interacts with interface of application which is created in programming language.
-The database always remains backside and do not come in front of the user. Hence the database is known as backend while programming language is termed as frontend.
-To understand the purpose or need of database system, we need to study the previous option to store data which is called as File Processing
System.
File Processing System:
-In our day to day life, number of times we need to store data in such way that it should be easily. accessible whenever required.
-After invention of computers, it becomes easy tostore data with the help of files. In the early days, database applications were built on top of file systems.
-Traditional File Processing System is a computer based system in which all the information is stored in various computer files.
-It stores data in a systematic way that the different departments of an organization can store their data in set of files which helps to manage anddifferentiate the data.
-The data may be of bank transaction details, daily expenses, employee details, product details etc.
1. Data Redundancy
- Sometimes as per requirement same data may be stored in multiple files. Consider an employee having record in both Employee and Team files. The name and address of employee is stored in both of these files.
- Means the data get duplicated. If such data increases, it leads to higher storage and access cost. This duplication of data in various files is termed as data redundancy.
-In traditional file system, it is very difficult to avoid this data redundancy.
2.Data Inconsistency
- When data is to be updated the data redundancy may lead to data inconsistency. Data inconsistency occurs when data is not updated in all the files simultaneously.
- For example if the designation of employee get changed, then the respective changes. should be made in both Employee and Team file. If for some reason, it is not done, then it leads to data inconsistency..
-Because for the sample employee, we may get different information which may create problems in the processing of data.
3.Limited Data Sharing
- It is difficult to share data in traditional file system. Each application has its own private files and users have little choice to share the
data outside their own applications.
- To share data, we have to write complex programs.
4. Difficulty in Accessing Data
- The need of data access varies time to time. Means different types of information is needed at different situations.
-For example, just consider that we want to retrieve the data of employees who do not have taken any leave throughout the quarter. In such case, we have two options.
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