What is Website Addressing and its Types

As we all know about the browser that interprets the html code to display the content written in HTML code to user. This content layout is called a Webpage or the content displayed on browser window called Webpage. These webpages collectively called a Website.

Website Addressing-   

The Address that is used to access the file or resource or the server machine on internet by using URL called the Addressing or Website Addressing. The URL hold an address that locate the server machine on internet and only this address machine is identified on internet. This address can be directly written in terms of IP (Internet Protocol) Address or by Domain Names provided by DNS System to Particular IP Address or Machine on Network.

The URL can be divided into Domain Name, Subdomain Name and Domain Name Extensions. 

For an example in URL :- https://bcomcomputernotes.blogspot.com, The https is a protocol used to transfer the HTML Code from client to server or server to client Machine with Security, .com is extension of Commercial Domain Name and the bcomcomputernotes is a subdomain of a blogspot domain.

Types of Website Addressing- 

Types of Website Addressing

1. Absolute Addressing

This kind of addressing is used when you are trying to redirect on server machine first time. It means the Absolute addressing contains the http protocol, complete domain name and file name with extension. This addressing is used to connect first time the resource machine or server machine on internet. If we ant to access the server machine, we use this addressing called Absolute Addressing.

Example of Absolute Addressing-

<a href="https://bcomcomputernotes.blogspot.com/p/home-page.html">

2. Relative Addressing

This kind of addressing is used when you already reached the server machine by absolute addressing and now want to redirect to access other folder or files. This redirection is done by the addressing called Relative addressing. In this addressing you do not need to put complete domain name as needed in Absolute addressing. By absolute addressing you have to put only the folder or file name that automatically redirect to that particular folder or file name.

Example of Relative Addressing-

<a href="/p/home-page.html">

Website Addressing Types using Diagram Representation

Three Layer Architecture of Database System

This Database Architecture is called three level architecture because of three layer implementation in this:

1. External Level (also called External Schema or View Level)

2. Conceptual Level (also called Logical Schema or Logical Level)

3. Internal Level (also called Internal Schema or Physical Level)

Three Layer Architecture of DBMS

Let us discuss each layer one by one-

1. External Level (also called External Schema or View Level)

This layer is topmost layer of DBMS system where view of logical level will be shared or displayed. The user or viewer desired result is represented as a view at this layer which is generated by fetching from Database or Logical Level. There are number of viewer can be exist for single conceptual level. The mapping between the View Level and Conceptual Level helps as a channel to get a result in view form from logical level database. This Layer is also called abstraction layer because it only display required view and hide the remaining information from user. The user do not need to know about from where data he gets or what the data structure (or schema) is used to store data. 

2. Conceptual Level (also called Logical Schema or Logical Level)

This Layer is Middle layer of DBMS Architecture where the structure of Database is logically defined. It also ensure the Data Structure used to store the Database, the index definition, Constraint implementation, Security etc. are the role responsibility of this Layer. The DBA (Database Administrator) is responsible for all these responsibilities at this layer.

3. Internal Level (also called Internal Schema or Physical Level)

This Layer is Bottom Layer or Lowest Level of DBMS Architecture that show how the data actually stored in Hard Disk. This Layer is responsible to allocate memory to data and its storage location. 

Operation on Files or Folder

In windows operating system, we can perform various files or folder related operations like copy, delete or move a file or folder. The GUI features provide facility to computer user to perform such kind of operations easily.

Let us Discuss each operations-

Copy or move a file or folder- This operation works for files and folder to copy files or folder from one location and create a same copy at destination place. While the move operation on file or folder just take file from one location and put it into destination location. These operations are done by either copy/paste and cut/paste option inside file organization (windows 7) or Home menu (windows 10).

Steps to copy or move file or folder-

1. Open the drive or folder in which file or folder exist.

2. Select file or folder yo want to copy by one left mouse click.

3. Available options

A. Copy/Paste- Click on Copy option given in Home menu or use shortcut Ctrl +C to copy file or folder. You can also copy file or folder by click on copy option displayed after right click on file or folder and open destination drive or folder and paste copied file or folder either by click on paste in Home Menu, shortcut Ctrl + V or click on paste option displayed after right click on destination drive or folder. 

B. Cut/Paste- Click on Cut option given in Home menu or use shortcut Ctrl +X to copy file or folder. You can also copy file or folder by click on Cut option displayed after right click on file or folder and open destination drive or folder and click on paste copied file or folder either by click on paste in Home Menu, shortcut Ctrl + V or click on paste option displayed after right click on destination drive or folder.    

C. Move Using Drag & Drop- Open the destination folder or drive in other window and drag the file that you want to move and drop it to other window.

D. Delete - You can delete selected file or folder either by click on delete option in Home menu or by click on delete option displayed after right click on file or folder that you want to delete. 

Data Independence in DBMS

Database architecture is generally designed in different layers so that each layer can work separately and if changes required at any level or at any layer than no problem would be encountered due to separation between the Layers. This separation provides the Data Independence. As we Learnt the Architecture of DBMS where three layers are used View level, Logical Level and Physical Level.

Data Independence means, if changes required at any level or at any schema than no other layers or schema will be infected by changes. The separation or isolation is required from application layer because no need to show the structure of database or its storage.   

Data Independence

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Types of Data Independence

1. Logical Data Independence- It provide the ability to DBMS system that if any changes required at the Logical Schema or Logical Level than do no need to change the application program or view level. It means the External level or application program do not need to modify itself if changes done at logical level. In other words we can say the changes done at logical level will not generate any problem at external level due to the logical data independence. Example changes done in table will not required to modify the view for viewer at view level or External Level.

Logical Data Independence

2. Physical Data Independence- It provide the ability to DBMS system that if any changes required at the Physical Level or Physical Schema than do no need to change the Logical Schema or Logical Level. It means Conceptual Level or Logical Level do not need to change itself if changes done at Physical Level or Physical schema. In other words e can say that the changes done at physical level like storage structure modification, index modification, changes in accessing methods, changes in data structures etc. will not generate any problem at Logical Level de to the Physical Data Independence.   

Physical Data Independence

Operating System & Its Important Functions

Operating System

An Interface that provide a channel between Computer Hardware and Computer User so that Communication is possible between these two is called Operating System. 

We already know that  Computer hardware performs the human task and gives the result but human can not drive the hardware directly for this human needs a channel called Operating System. 

The middle layer that takes user task as input and instruct the hardware to processing is called an Operating System.

An Operating System also works as a controller to all programs which are used by human like MS-Word, Excel etc.

Operating System

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Functions of Operating System

Functions of Operating System

Let us Discuss one by one deeply-

👉Provide Interface to User- It works as an interface to computer user so that user can communicate with the hardware. In absence of Operating System user can't do anything.

👉Process or Processor Management- when number of processes running on same time (multi- programming System) than the duty of operating system is to process the every process without any conflicts or deadlock. For this, Operating system works on process scheduling algorithms. In multiprocessing System where number of processors are arranged for processing the processes, the operating system provide the processor to process in such a way that utilization of each processor should be done. Other processor management tasks are tracking process status(process is executed, running, pending, aborted etc.), processor allocation and deallocation for which process.

👉Memory Management- The Operating System is responsible to manage the memory according to requirement of any software. The Memory allocation for any process or program is provided by operating system and if process or program execution is completed than the memory occupied by processes are deleted by Operating System. Operating System also responsible to check the memory utilization, how much memory provided to process etc.

👉Device Management- The proper management of Devices and device drivers functioning related management also under the care of Operating System. Input/ Output Controller is used to track the devices. Operating System ensure the device allocation and deallocation for process.

👉File Management- The OS is also responsible for file management. The files which are stored in directory structure are utilized by operating system. The Tracking of file is done by operating system as well as its status (open/close), its location, resource provided for files operation( like printer), files allocation and deallocation related management etc.

👉Coordination between other software- The OS take care the mapping and coordination between the software. For an Example if you are using code editor that need application software and this code is compiled by compiler which is a kind of System Software. These software coordination is required to execute the code and this is done by Operating System.

👉Security- The Operating System Provides the functionality to create user account to protect your files.

👉Job Accounting- It take care the jobs and the resources hold by the Jobs. It also count the resources and processes who consume it. IT keep record in Resource Allocation Table and Continuously update it.

Except these functions operating system also works for Linker, Loader, Compilation, error message display, control the system performance, etc.               

Plotter and Its Types

Plotter

Plotter is an output device mainly work for printing the graphics content which is of Vector form. Vector Graphics basically uses the sharp lines, curves, shapes to draw an image. By using the Plotter you can print a vector graphics or vector graphic image. Plotter is the first output device which is used to print the vector Graphics content. The plotter not used for printing dots or raster images, it is generally used for Vector graphics in which continuous lines exist to draw an image. Plotter are very costly to purchase and only the big scale organization can buy this. The application of Plotters are Car Manufacturing, Computer Aided Design, Geographical Representation, Earthquake estimation on graphics etc.

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Types of Plotter

Types of Plotter

👉Drum Plotter- As the name suggest, its having a drum as a mechanical part. This drum is used in both the direction ( forward and backward direction) to plot the drawing. The drum plotter is also called roller plotter because of having roller or drum in it. Paper sheet is placed on the roller and roller movement draw on Paper sheet. A mechanical part called Arm is used in Drum plotter for movement of drum in both the direction to draw vector graphics on Paper sheet. This arm having pen and pencil with different colors that move side by side in both direction when roller moves. The ink is used by Arm to plot the continuous lines for creating vector graphics. The Example of using Roller Plotter to represent Earthquake activity by drawing.

👉Flatbed Plotter- This plotter is tabular format like bed sheet. It is having 20-50 feet tabular sheet on which continuous drawing is done by plotter called Flatbed Plotter. It contains two mechanical parts or Arms that have the pens or pencil containing different set of colors to draw the image. These arms are movable and plotting the color on stationary or fixed paper sheet. Its working is slow as compared to Drum Plotter because it contains two arms that consume more time in movement from one coordinates to another particular coordinated on paper sheet. It is used in mainly in big scale drawing like Car designing, Ship designing, Building structure design, etc. that is why it take long time even several hours to draw an Image.          

    

Importance and Advantages of DTP

Desktop publishing has number of importance and advantages but before start, we can understand about the DTP by its definition and its types.

DTP Definition 

DTP is an Acronym of Desktop Publishing which can be break in Desk + Top + Publishing that gives the complete meaning of DTP i.e. the publication on Desk by using Computer System. DTP is used to create the electronic forms by selecting different layout styles and applying the graphics on it so that it can be printed by using printer. DTP follows the WYSIWYG (What You See Is What You Get) feature in Hard Copy or printed paper. DTP allows user to create Brochures, Documents, presentations, Banners, Letters, Templates, Pamphlet design and many more. Book publishing and press publishing also uses the DTP software to creating the layout according to use. 

Types of DTP Pages-

Types of DTP Pages

According to the Page Content, we can categorized DTP into two pages namely Electronic and Virtual Pages. Let us understand pages one by one-

☝Electronic Pages- The electronic pages means the pages are used in Digital world like eBooks, Website Pages, online Presentations and digital archives etc. These pages are electronic pages because it is not created for printing purpose. These pages are used for online content creation.

✌Virtual Pages- These pages are used to create for Printing purpose. The virtual pages are actually used to follow the property of WYSIWYG (What You See Is What You Get) that illustrate about the hard copy of document is the complete reflection of soft copy(document) created by DTP. Virtual Pages are mainly used for Printing Press, Books Publication, Magazine, Nobel etc.

Importance of DTP

Importance of DTP can be judge by its application in different sectors. The DTP cover the number of sectors for printing the documents or Digital documents creation. The list of Applications that shows the importance of DTP are-

👉Printing Press- The press highly uses the DTP software to create the News Paper on daily basis. Number of News Paper agencies are in market today that shows the importance of printing document creation by DTP.

👉Business- In Business The number of documents are created by DTP software like Legal Certificates, Bond Papers, Authorized Papers, Advertisement Cards etc.

👉Crafts Design- The paper cutting is used to make a good art, generally this is used in kids school. Where Pages designed by DTP software are used to create an impressive art. This is called Crafting and it can be used at several places like home decoration, party decoration, office decoration etc.

👉Personal Projects- We can also use DTP software in such projects where thesis is required in Good Quality and put the Graphics Quality in it. The projects like Greeting Cards, ID Cards, Invitation Cards etc. 

👉Education- In Education sector number of uses of DTP software exist like Brochure, Template, Notes, Books, Presentations, Graphics uses for Article etc.            

👉Career Assistance- We can create Resume, Applications, Letters etc. for our career prospective. The Organizations firstly check the profile of Interviewer by seeing his Resume that provide chances of getting job. For an Example if you are going to face an interview for computer field but in your resume you are not using expert formatting than there will be less chances of selection for that post.

👉Graphics Creation- The DTP software highly used for its graphic quality. The number of  uses for graphics creation are Newspaper, Website Content, Profile pics, Wallpaper, presentation, Brochure, pamphlet etc.

Advantages of DTP 

DTP software has many advantages over normal word processing software like fast document creation, easy customization, Layout etc. Let us discuss major advantages of DTP-

👉Speed- You can create document in less time. The reason behind this is the easy customization of Document. You can drag and drop the object in document without wasting time.

👉Easy Customization- If you are using DTP software for document creation than yo can easily create it by using required customization. Customization means can se different formatting, layout, margin etc. according to user requirement. This feature gives more value to the DTP software.

👉Page Layout- You can use any layout to arrange the text on it. The Layout basically used for content like text or graphics arrangement in the same page. Page Layout attract the stranger to become your customer.

👉Reduced Production Costs- If you design any document than its easy customization and fast creation save production cost. No need to do hard work on production of any kind of document if you are using DTP software. .         

Introduction to Word Processing

Word Processing

Word Processing is a term used to express the word processor activities on document like document creation, document editing, document formatting, document printing etc. The main Components of word processing systems are word processor, printer and a computer system.

Word Processor is a special program that work on word documents and perform the basic operations on it. Word Processor provide the functionality to create a document, edit if required, display it on screen (monitor),  store it in Hard Disk (electronically), type the characters or commands using keyboard and print the document using printer. 

Some of the basic word processor functionality listed below-

👉 Copy/Paste & Cut/Paste- This basic feature of word processing is used to copy content from one place and place it on another place by sing paste option. On other hand Cut option is used to remove text from one place and place it on other place by using paste option.

👉 Find & Replace- This option is used to search text in document by find option or Ctrl + F . The text you ant to search just type in textbox inside find dialogue box. On other hand Replace or Ctrl + H is used to find text first and the write text that can replace the find text.

👉 Printing- This command is used to instruct the printer to print the document.

👉Insert & Delete Text- By this feature you can insert or delete text at any location inside the document.

👉Word Wrap- This feature is used to wrap the text or cover the text using boundary. Whenever your text is out of line it will auto adjust in line using word wrap option.

👉Margin setting- Margin feature is used to create margin from left, right, top or bottom side if required in a document. 

👉Page Size setting- There is also an to adjust the page size according to the requirement for a document.

The above listed basic features are provided by basic word processing software called Text Editor. But if we talk about the standard features of standard word processor than there are a lot of features that are provided. These standard word processing software are called advance word processing software or full featured word processor which have additional features and functionalities like formatting, manipulating document, text alignment, line spacing, paragraph spacing etc. Let us discuss all the standard word processor features given below-

👉Document Formatting- This feature provide different kind of formatting like text formatting (italic, bold, underline, subscript, superscript, lower case, upper case, capitalize first letter of each word) and paragraph formatting (alignment, line spacing, coloring, paragraph ending identification etc.).

👉Mail Merge- This feature provide you to prepare a letter or document and send it to many recipient. This feature provides the isolation of mail between the recipient.

👉Document Layout Setting- You can set document Layout through margin (left, right, top or bottom) and even can set layout by intending the text from either of the direction.

👉Spell and Grammatical Checker- These features are very helpful for those user who have less knowledge of grammar and word vocabulary. By this feature you can check spelling of word and can correct grammatical errors if have.

👉Embed Object feature- full featured word processor also support object embedding option. Object like image, clip arts, smart arts, chart can be embedded in document if required.

👉Header, Footer and Page Number- These features are used to provide header, footer and Page numbering in documents like Title is written in Header Section, Publication is written in Footer Section, Page numbering to identify page number in different number format or alphabet format.

👉Macros Feature- This feature is used to provide time saving command. Macro is a set of keystroke or characters which is used as a command or replacing long text whenever needed.

👉Table Layout- Is used to insert table in document for indexing and other purposes. Word Processor has many option to create it.

👉WYSIWYG- What You See Is What You Get means the document display on monitor will be reflected in hard copy after printing.

👉Page Setup- In this feature you can set the page by using Page Size, Page Orientation (Portrait, Landscape), One page with Columns.

👉Windows- This feature support user to work with different document on different window.

👉Bookmark, Water Mark & Page Border- These features provided in Word Processing to create a page border, Create book mark on page and create water mark to symbolized copyright.    

                

File System v/s Database System

File System

This system adopted after the the se of punch cards for storing the information in 1960's. In this system files are managed by software and the operation performed like insert, update, delete etc. are done manually. The advantages of this kind of system is easy data handling and having good security. Easy data handling is possible because the the work done by human manually. But in file system there are number of disadvantages like data redundancy (Data Duplication) is high, data inconsistency is high, unable to maintain data integrity, only application for small business like local shop etc. Le s understand these points one by one that completely express file system- 

1. File System adopted in 1960's for easy data handling manually.

2. The files are stored in Hard Disk Drives and managed by software and provides security.

3. All the operations like storing, searching or retrieving information is done manually and not highly technical skills were required.

4. Only one record is maintained in one file and hence many files were used to store many records.

5. Data Consistency is not achieved in this system because manual checking of data is not easy.

6. Data Redundancy is also not achieved in this system due to the possibility of having one record in more than one files and its manual checking is time consuming.

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Database System

To overcome the issues created in File System, database system is in use. In the Database systems software manages the databases rather than files. Database system can not be used by normal human, for using this system human must be skilled in database technology. The Database System is very useful because it provides less redundant and consistent data as compared with file system redundant and inconsistent data by using Normalization process. The integrity is also achieved by database system but there is a problem i.e. the SQL Language knowledge is must for user. This process is semi manually process because you have to use any SQL command that can be performed by SQL Engine on Database to access, insert, update or delete operations. Let us understand Database System point by point-

1. Database System Come in Market after the file systems.

2. Database system provides the Data Consistency, less Data Redundancy and High Data Integrity.

3. Database System are used in large scale organization where the need of huge amount of data to be stored. 

4. Database System also supports other operations like TCL (Transaction Control Language) and DCL (Data Control Language) etc.

5. The Database management is a complex process.       

       

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Difference between File System v/s Database System
Topic	File System	Database System
Definition	A system that manages the data into files inside the HDD and perform the file related operations.	A system that organize the collected data into a structure inside the database and perform the database related operation using SQL query Language.
Data Sharing	files are located in local system hence data sharing is not done.	Databases are stored in centralized system hence sharing is allowed in Database System.
Data Security	Files are stored in local system so it is secured if no other person use local system otherwise it is not secured. Majorly we call File System is insecure if files stored on Network.	Data stored in Database which is located in centralized system and only authorized user (using username and password) can access it. Hence it is more secure.
Data Consistency	Data consistency is very poor in the file system. For an example, If one person information is stored in more than one file than we have to change the information in all the files of particular person if required otherwise one person information is different in different files.	Data consistency is managed in database system. Because we can store data into centralized location.
Data Integrity	Data integrity is not maintained in file system.	Data integrity is maintained by DBMS system.
Data Redundancy	Data Redundancy (Data Duplication) is a major problem in file system.	Less Data Redundancy is exist in Database System.
Normalization Process	Normalization process is not used in File System.	Normalization process is required to maintain Remove the Data Redundancy and to Achieve the Data Consistency.
Application	It is used in small scale organization like local shop or locality information.	It is used to store at large scale organization like college, university etc.
Backup & Recovery	In File System, Backup & data recovery process is not good. If data is removed than there is less chances to recover complete data.	In this system Data Backup & Recovery is possible. In case of system failure backup is used to restore or recover the lost data.
Structure	Simple Structure is used to store data i.e. file.	Database structure is complex and normal human can not understand it.
Query Language	No any query language is required.	Database system required a Query Language known as SQL (Structure Query Language).
Data Abstraction	Data abstraction is not provided in File System.	Data Abstraction is possible in Database system. Only user required information is accessible other information is hidden to provide data abstraction functionality.
User Interface	Single User Interface is provided in File System hence called Isolated system.	Multiuser interface is provided by Database System so that multi user can access at the same time for same database.
Concurrency Control	Concurrent Access is not achieved in File System	Concurrent access is possible in Database System.
Transaction Control	Transaction Control Not possible in File System.	Transaction Control is achieved in Database System using TCL commands.
Data Control	Data Control not possible in File System.	Data Control is achieved in Database System using DCL commands.
Examples	NTFS, FAT & FAT32 etc.	MS-SQL, Oracle & MySQL etc.

Strategic Database Planning

We know that all the organization have their database resources through which they can store and manage their organizational data and maintain it. But these resource creation is purely work on needs of organization. These needs gives a result called Database. But to fulfil the needs we have to follow some basic rules or strategy so that needs of organization will be easily achieved.

When we are working on database creation for any client requirement than we have to follow some steps in sequential manner so that our database provide all the functionality according to client requirement with efficient and accurate result. 

Let us discuss such kind of strategies or sequential steps planning that create a Good Database-

1. Business Plan

We know that everything will be created after the plan. If client wants a database than client must have a good plan according to that plan client needs a Database. For an example if client want to open an organization like college than client have a plan like financial plan, property plan etc.

2. Information Needs

To work on this plan client must have useful information or required useful information so that its plan work successful. In our case client needed useful information for his organization (college) like how many courses is required which course have good scope, how many universities provide that courses, ho many staff members required, departments required etc.

3. Database Plan

Now the client have done his duty after showing information needs for his organization and after that the Database developer will a play role. Database Developer will understand all the plan and information needs and start to create his plan for making good database. This plan can be called as database blueprint. This plan contain the description about how many tables are required to fulfil client needs, mapping between tables is required or not, default values are required to store or not, how many users are required to access this database like manager, employee, admin etc.

4. Project Implementation or Database Implementation

Till this step database developer has full knowledge about the client requirement for his plan and on that requirement developer created his database plan. Now this database plan is implemented by developer as a project so that client can use it for his organization. In this implementation, Developer must have the complete database knowledge so that he can create such structures like for department table creation developer must ensure the primary key for Department ID, Not Null Constraint for Department Name etc. Similarly in Employee table, Employee ID must be primary attribute, Employee Name must contain not null constraint etc. After complete this database development, database will be  used to store and maintain the organization records according to the client plan.

Strategic Database Planning

               

Risks and Cost of Database

Data storage in well organized manner is done by Database but this is not an easy process. It is a very complex process and having high risk to maintain. The Cost management is also required to manage the database cost effectively. So These two factors are very important in terms of Database System. Let us Discuss about the Risks and Cost of Database-

1. Hiring of Trained or Specialized Personnel 

As we know that every organization have some experts who are responsible to maintain the Database of the Organization and at the same time organization is also responsible to hire such trained Employees who can manage the organizational database efficiently. In the hiring process the organization also checks the hired employee must be updated and having the knowledge of current database technology so that if database upgradation is required than no problem will be encountered.

2. Database Installation & its Management costs

The installation of database is required at appropriate drive where the large memory exist and also install the database at the right platform. If we wrongly select platform than installation is not possible for Database System. After Installation of Database in Correct platform there is also need to manage it correctly and accurately and for this kind of management some costs will be used for either operator or person who install or manage it. We know that every software has some cost similarly database software, its installation and its management will take some more cost. The Hardware cost is also required if we install Database on some hardware system. 

3. Technology Conversion Costs 

We know that Database server uses different technologies and the organization try to move on new technology but the database which is designed in old technology like file system can not easily moved towards new technology it takes time and the process of database conversion between technology needs some costs. This cost is called the Database or technology upgradation costs.

4. Organizational Conflictions

There are number of organization which are working together or sharing same database but this generate confliction between these organizations like how data will be store or  manage and who will take this responsibility. Some other cases also exist to create confliction like which data definition is up to the mark, how data will be organized, which technology will be preferred to store the data etc.

5. Requirement of Explicit Database backup and Recovery 

Backup and Recovery is really helpful when server failure or hard disk failure occurred and that moment if we have backup than we can restore our data by using  recovery process. But if we do not have backup and Recovery option than we can not get our data back after loosing it.

6. Complexity of Database System 

Database storage is not an easy step it is complex process that work in background and of course this complexity is not understandable by normal user hence there is also requirement of an expert person or developer who can manage and store the data without any problem.

Risks and Cost of Database

              

Introduction, Need and Application of DBMS

DBMS is a place where data is stored and at the same time data is maintained. DBMS also provides facilities to organize data by using the insert, update and delete commands. In other words, we can say DBMS is used to store data efficiently and retrieve it effectively.

Database Management System is a software tool developed by different organizations to store and maintain data efficiently and provide features like security, integrity etc. Now a days number of DBMS systems are used like MS-ACCESS, MS-SQL are Microsoft Products, Oracle and MySQL are Oracle Products etc.to store and maintain the data.

Basic Components of Database Management System

We know that every software tool have some components similarly DBMS also comprises some basic components which are given below-

1. Users- 

Users may be Naive user, Application Programmer, Database Administrator etc. Those uses Database System and perform queries on it.

2. Database Application- 

This is used to provide an interface through which you can access the Database Management System that can be further categorized by organization level, manager level etc.

3. Database Management System- 

The Software tool which is used to store data and organize the data generally in tabular format. 

4. Physical Storage- 

Where Data is Collectively stored as a single Unit.

Basic Components of DBMS

Need of Database Management System

DBMS is needed in daily life to maintain the record at a single place. The number of functionalities provided by DBMS which are-

1. High level Insertion, Deletion and Updating.

2. Providing the Data Consistency

3. Providing data Integrity and Security

4. Providing Concurrency Control and Access.

5. Providing Transaction Control

6. Providing Managerial Control on Data

7. Providing Data Independency at both logical and physical level.

8. Providing Redundancy Removal features or Store less redundant Data etc. are the needs of DBMS.

Application of DBMS   

1. Schools, College, Universities- These Educational Organization store Data in DBMS System.

2. Airline System- Where Ticket Booking, Scheduling of Flights etc. is stored in DBMS.

3. Hospital- Hospital or in Medical Organization where Medicine, Doctors, Patients etc. information is stored in DBMS system.

4. Agriculture Field- Where Seed information stored in DBMS.

5. Data ware House & Data Mining- which collect all the Data which is stored in different DBMS and perform mining techniques to predict pattern and take profitable decisions.

6. Railway System- Where ticket Booking, Schedule of Trains, Passenger information is stored in DBMS.

7. Banking Sector- Where Customer Account, Policy Information etc. are stored in DBMS.

There are number of Application exist where DBMS play a vital role.

Codd's Rules in RDBMS System

 Codd's 12 Rules in RDBMS System

The Computer Scientist Name- E.F. Codd (Edgar Frank Ted Codd) who invented the Rules for Relational Database Model on the behalf of these rules any DBMS system are Called either RDBMS or Not. There are Total 13 rules but due to its first rule i.e. zero (0), We call Codd's 12 Rules.

These rules followed by DBMS system and if more than 6 rules are followed by any DBMS System than these DBMS systems are called RDBMS (Relational Database Management System) systems. Relational Database created based on Relational Model must follow the codd's 12 rules.

Codd's Proposed these 12 rules to show the quality required in DBMS to become it as RDBMS System. If these 13 rules are followed by any DBMS system than this system has highest quality of RDBMS but eventually there is no any kind of DBMS which follows all the Rules. Even the RDBMS system we are using called Oracle only follows 8 or 8.5 rules out of 13. Let us understand what are rules defined by E.F. Codd for DBMS System.

Codd's 12 Rules

Codd's 12 Rules in RDBMS System

Rule Zero- Foundation Rule:-

This rule states that the RDBMS system must manage the Database Completely using its relational capabilities. It means DBMS system is qualified as RDBMS if it follows this rule by using relational capabilities whole database is managed.

This rule is called fundamental rule because the remaining rules are based on this rule.

Rule 1- Information Representation Rule:-

This Rule illustrate that the Information must be stored in well representative manner. It means all the information stored in RDBMS system inside cells of a table. The Information including metadata is stored in Logical Level in cells of a table.

Rule 2- Guaranteed Access-  

This Rule illustrate that fetching of data will be possible at any time by giving the Table Name, Column Name and Primary Key. It means data must be available when Table Name, Column Name and Primary key is used.

Rule 3- Systematic Treatment of NULL Values-

This Rule illustrate about proper management of NULL values. The Null value must be distinct from 0  or empty string. The Null value will be used where the value is not provided or missing data or not applicable value. Null value must be represented by NULL not by 0 or empty string or by any other number. Primary key must contain NOT NULL value. So NULL value treatment is required in RDBMS System.

Rule 4- Active Online Catalog-   

This Rule illustrate about the Database description or information of Database structure will be stored online in Catalog. The Catalog is nothing but the Database Dictionary where all the structural information of Database is stored. The Catalog can be accessed by Authorized user. User can access the Data Dictionary or Catalog by same query as the query used to access other Database objects.

Rule 5- The Comprehensive Data Sub-Language Rule-

This Rule says that the Database must provide support for the languages which follow the linear syntax and have the ability to perform Data Definition, Data Manipulation, Data Control and Transaction Controlling operations. The Database must be accessed by these language either by directly or by using any third party applications. Point to be noted here if it is possible to manipulate the Database without using these supportive language than this is the violation of this rule.

Rule 6- View Updating Rule-

This Rule illustrate about the view concept of Database and states that if all the views in database updated theoretically than it also updated in Database System at system level.

Rule 7- High-Level Insert, Update and Delete Rule- 

This states that there should be high level support for Insert, Delete and Update Relational Queries. RDBMS also support the Set operations like Union, Minus and Intersection.

 

Rule 8- Physical Data Independence-

This rule says that the physical storage should not create any problem to system when the supporting table for a file is renamed or moved to other disk.

Rule 9- Logical Data Independence-

This rule illustrate that if any changes done at logical level( structure of Table) than there is no problem at the view level. It means if we have a view of a table and we want to split that table into two tables then there will be a new view which will be showing the same result by merging these splitted tables.

Rule 10- Integrity Independence-  

This rule states that RDBMS should have the ability to enforce its own integrity using own programs rather than other programs. There are Primary key, Foreign key, Not Null, Unique, Check, Trigger constraints are stored in Catalog or Data Dictionary. It means by using integrity, RDBMS system independent at front End.

Rule 11- Distribution Independence-   

This rule says that the Database distribution on Network (like Geographically) should not create any problem and it should work properly to user so that user feel like the data is stored at single location.

Rule-12- Non-Subversion Rule-

This Rule states that if any lower level programming or procedure is allowed or exist than it should not  bypass or unable to bypass the integrity rules provided by the RDBMS System on Database. 

   

  

TCL Commands in Oracle

 TCL Commands in Oracle

What is TCL Command

TCL Command means Transaction Control Language which are used to maintain transaction processing in Databases. TCL commands are required when wrong DML commands are fired or transaction failure occurred and we want undo the changes which are recently done or restore last records before processing the wrong commands. I hope now you understood why TCL Commands are highly required in Relational Database Management System.

In TCL, There are three commands-

1. SAVEPOINT - This command is used to create a point and assumed till that point all the data are correct and there was no problem with that data. If we fire further DML queries on Table and suppose there is some kind of failure occurred or executed DML query is incorrect than we can undo the changes which are wrong and get our last correct data by reaching the point called SAVEPOINT.

Syntax of SAVEPOINT creation-

    CREATE SAVEPOINT Savepoint_Name;

2. ROLLBACK- This Command is used to jump to the point called SAVEPOINT which is provided at the time of Rollback command execution. After creation the SAVEPOINT there are some DML queries are fired but in these queries if any query executed wrongly than we uses the rollback to get the last committed data.

Syntax of Rollback Command-

    ROLLBACK TO Savepoint_Name;

3. COMMIT- This command is used when we ensure about the DML queries fired correctly and there is not any kind of failure occurred. In other words we can say that we want to save data permanently after the updates that occurred due to the execution of DML Queries on Table.

Syntax of Commit Command-

    COMMIT;

Let us understand step by step by taking an example- 

1. Create a table called Employee by given command-

    CREATE TABLE Employee

    (

        EmpID INT PRIMARY KEY,

        Name VARCHAR(20) NOT NULL,

        Mobile NUMBER(10) UNIQUE,

        Salary NUMERIC(10,2) NOT NULL,

        City CHAR(20)

    );

    after execution Employee table will be created.

2. Insert to records inside Employee table by given commands-

    INSERT INTO Employee VALUES ( 1,'BHUMIKA', 1234567890, 16000, 'BHOPAL');

    INSERT INTO Employee VALUES ( 2,'MONIKA', 1234567892, 18000, 'INDORE');

    after executing each command one row will be created hence to rows will be created overall.

3. Now we want to see the record of Employee table by given command-

    SELECT * FROM Employee;

    Now we get the result like this-

              

EmpID	Name	Mobile	Salary	City
1	BHUMIKA	1234567890	16000	BHOPAL
2	MONIKA	1234567892	18000	INDORE

4. Now we are going to create a SAVEPOINT called S1 by given command-

    SAVEPOINT S1;

    after executing this command we get a SAVEPOINT created message.

5. Now we are going to execute update (any DML) command by given below-

    UPDATE Employee SET Salary=20000 WHERE EmpID=1;

   

    when we execute this command we get a message of successful update. To confirm this we can select

    Record from Employee Table by given below command-

    SELECT * FROM Employee;

EmpID	Name	Mobile	Salary	City
1	BHUMIKA	1234567890	20000	BHOPAL
2	MONIKA	1234567892	18000	INDORE

As seen the above table that the record is updated but at this point we realize that there is no need to increase the salary of Employee whose EmpID is 1 than we called Rollback command to get our record back as before the creation of SAVEPOINT S1.

6. Now we called Rollback Command by given below-

    ROLLBACK TO S1;

    After executing this query Rollback completed message will be appeared. For confirmation rollback

    is done or not we can fire select command again by following below command-

    SELECT * FROM Employee;

 

EmpID	Name	Mobile	Salary	City
1	BHUMIKA	1234567890	16000	BHOPAL
2	MONIKA	1234567892	18000	INDORE

    As we can see the after the rollback command we get the same record as before the SAVEPOINT

    creation means there is no affect of update command after rollback.

    But in case if we want to save data permanently after the update command than we can use the

    commit command at the place of Rollback command (step 6) as given below-

    COMMIT;

    This command permanently save the updated record after this command execution, Rollback

    command is useless and will generate an error.  

Let us Check These Commands in Run SQL Command Line-

1. Below Image show the use of Rollback Command-

TCL Command Rollback Example

2. Below Image show the use of Commit Command-

TCL Command Commit Example

As we can see there is an error after commit command when we use rollback command. 

Font Tag in HTML

 Font Tag in HTML

Font tag is very helpful hen you want to write some text in different font style like Times New Roman, Verdana, Arial etc. Also you can set the color and size of fonts by using font tag attributes. Font face only works if it is installed in your machine or system. 

In HTML programming, you can use <font>  to implement font tag.

In HTML programming if you want to set styles for font tags in complete document than you can use base font tag. This style will be inherited by every font tag in document if font tag is not having self styles. For this we use <basefont> tag in HTML. <basefont> tag is older tag and it is supported by HTML4 version not in HTML5 or more.

Note:- Instead of using font tag you may use CSS style because font tag will be not applicable after some time due to CSS.

<basefont> and <font> both tag contains same attributes. <basefont> tag does not have closing tag.   

Attributes of Font (<font>) Tag in HTML-

1. Face - This attribute set the font-family like Times New Roman, Arial, Verdana etc. for fonts.

2. Color - This attribute set the color of text or fonts written between the opening and closing font tag. 

3. Size - This attribute set the font-size written between the opening and closing font tag. Size of font is

               by default 3 and its minimum value is 1 and maximum value is 7. You can use +(plus) and 

               -(minus) operator symbol before value that indicate increment and decrement respectively in

               default size according to size value. For an example we know that default font size is 3 and we

               use font tag with size= +2 than the text size will be 5 and if we use font tag with size= -1 than

               the text size will be 2.  

Let us Discuss about how to use the Font tag in HTML programming with its Attributes-

<HTML>

 

      <HEAD>

  

           <TITLE> Font Tag in HTML </TITLE>

      </HEAD>

      <BODY>

          

          

          <FONT FACE="TIMES NEW ROMAN" SIZE="1" COLOR="RED">

             Hello Viewers this text will be in Red color, Size will be 5 with Times new Roman font Style.

          </FONT> 

         

          <FONT FACE="ARIAL" SIZE="2" COLOR="BROWN">

             Hello Viewers this text will be in Brown color, Size will be 2 with Arial font Style.

          </FONT> 

          <FONT FACE="ARIAL" SIZE="+1" COLOR="BLUE">

             Hello Viewers now this text size will be 3+1=4 where 3 is default font size.

          </FONT> 

          <FONT FACE="ARIAL" SIZE="-1" COLOR="BROWN">

             Hello Viewers now this text size will be 3-1=2 where 3 is default font size.

          </FONT> 

    

      </BODY>

</HTML>

---

Output-

Font Tag Output