Table of Contents
A relational database comprises organized data items presented in formally defined tables, allowing versatile access and reassembly of data without necessitating a reorganization of the database tables. E. F. Codd introduced the relational database concept at IBM in 1970.
The structured query language (SQL) serves as the standard interface for users and application programs interacting with a relational database.
In this database model, tables contain data categorized into predefined fields. Each table, also referred to as a relation, consists of columns representing various data categories, while each row holds a distinct data instance for the defined columns. For instance, a business order entry database may have a table describing customers with columns like name, address, and phone number, and another table detailing orders with columns such as product, customer, date, and sales price.
Users can tailor their database view to meet specific needs. For instance, a branch office manager might seek a report on customers who made purchases after a certain date, while a financial services manager could obtain a report on outstanding accounts, both using the same underlying tables.
The manipulation of relations within the database is accomplished using SQL statements. Key SQL commands include SELECT for extracting data, UPDATE for modifying data, DELETE for removing data, and INSERT INTO for adding new data. Additionally, SQL includes commands for database and table creation, modification, and deletion, such as CREATE DATABASE, ALTER DATABASE, CREATE TABLE, ALTER TABLE, DROP TABLE, CREATE INDEX, and DROP INDEX.
The SELECT statement, a fundamental SQL command, is employed to retrieve data from a database. The resulting data set, known as the result-set, is stored in a result table. The syntax for a basic SELECT statement involves specifying column names and the corresponding table. For instance:
Integrity constraints (IC) are conditions defined in a database schema that regulate the permissible data in a database instance. A legal instance is one that satisfies all the specified integrity constraints on the database schema. The Database Management System (DBMS) allows only legal instances to be stored in the database.
The relational model accommodates various types of integrity constraints, which contribute to the validity and consistency of stored data. Constraints, often expressed as rules, uphold the integrity of the database by preventing violations. These constraints can be applied to individual attributes or relationships between tables, ensuring that authorized user modifications (updates, deletions, insertions) do not compromise data consistency.
For instance, consider the example where a blood group must be restricted to values ‘A,’ ‘B,’ ‘AB,’ or ‘O’ exclusively, excluding any other values.
Different categories of integrity constraints include:
Domain integrity encompasses the definition of a valid set of values for an attribute. It involves specifying the data type, length, allowance of null values, uniqueness, default value, range, and/or specific values for the attribute.
This constraint asserts that the value of a primary key attribute in any database relation cannot be null. For instance, in a “STUDENT” relation, the “Stu_id” primary key must not contain null values, while other attributes may allow null values.
This constraint stipulates that if a foreign key exists in a relation, the foreign key value must either match a primary key value in its home relation or be null.
Key constraints declare that a specific minimal subset of fields in a relation serves as a unique identifier for a tuple. There are four types of key constraints:
Various RDBMS vendors offer a graphical user interface (GUI) to assist users in query development, aiding novices in grasping overarching concepts without delving into syntax details. To facilitate this learning approach, our course commences with Microsoft Access, known for its exceptionally user-friendly interface.
Begin by downloading an Access database and examining its tables. Throughout this lesson, we will utilize a baseball statistics database to illustrate SELECT query fundamentals.
To view table contents:
– Double-click on a table name in the Navigation Pane to open it.
– Open all three tables and review their content.
Now, let’s write a simple SELECT query:
To set criteria and sort records:
It’s evident that the query output lacks user-friendliness. In the next part of the lesson, we’ll explore how to enhance the output by incorporating a join between the two tables to include player names in the results.
A computer file, characterized by a designated name known as the filename, serves as a repository for data or information within a computer system. Virtually all data stored on a computer takes the form of a file, and these files can encompass various types, such as data files, text files, program files, and directory files. Each file type is tailored to store specific kinds of information, with program files containing programs and text files housing textual content.
Definition of a Computer File
A computer file acts as a storage resource accessible to computer programs, typically residing in durable storage. The term “durable” implies that the file remains accessible for use by other programs even after the program that generated it has completed execution. Computer files can be likened to the contemporary equivalent of paper documents kept in office and library files, giving rise to the terminology.
File Organization
The term “file organization” pertains to the logical relationships among the records constituting the file, particularly concerning the identification and access methods for specific records. “File structure” refers to the format of label and data blocks, as well as any logical record control information.
Efficient file organization is crucial for optimizing base relations. For instance, organizing a file by student name facilitates alphabetical retrieval of student records, while other file organizations may be more suitable for different tasks. The selection of an optimal file organization is the primary objective.
To facilitate effective selection of file organizations and indexes, various types of file organization are presented:
An unordered file, commonly referred to as a heap file, represents the simplest form of file organization. Records are inserted in the file in the order of insertion, with new records added to the last page. While insertion is efficient, retrieval involves a linear search, making it relatively slow for files with numerous pages unless a large proportion of records are involved.
Pros of Heap Storage:
Cons of Heap Storage:
– Inappropriate when only selected tuples of a relation need to be accessed.
In a hash file, records are not stored sequentially; instead, a hash function determines the address of the page for storing each record. The hash field, acting as the key, undergoes a hash function to evenly distribute records throughout the file. This method is also known as random or direct file organization.
The Internet functions as a global network of interconnected computer networks, utilizing the Internet protocol suite (TCP/IP) to connect billions of devices across the globe. It encompasses diverse networks—private, public, academic, business, and governmental—spanning local to global scopes. This intricate network relies on various electronic, wireless, and optical technologies. The Internet serves as a conduit for a vast array of information resources and services, including the World Wide Web (WWW) with its interlinked hypertext documents and applications, electronic mail, telephony, and peer-to-peer networks for file sharing.
Web Browser:
A web browser, commonly referred to as a browser, is a software application designed for retrieving, presenting, and navigating information resources on the World Wide Web. Information resources are identified by Uniform Resource Identifiers (URI/URL) and may include web pages, images, videos, or other content. Hyperlinks embedded in resources facilitate user navigation to related content.
Anchor:
Synonymous with hyperlinks, an anchor denotes non-linear connections between documents. In simpler terms, it represents the clickable word or phrase linking to another page or resource.
ASCII:
ASCII, short for the American Standard Code for Information Exchange, is an international standard assigning numbers from 0 to 127 to numbers, letters, punctuation marks, symbols, and control codes. ASCII facilitates easy network transfer as plain, unadorned text without style or font specifications.
Avatar:
An avatar refers to an interactive representation of a human in a virtual reality environment.
Bandwidth:
Bandwidth denotes the range of transmission frequencies a network can utilize. Higher bandwidth allows for the transfer of more information simultaneously.
Baseband:
Baseband is a transmission method wherein a network employs its entire transmission range to send a single signal.
Broadband:
Broadband is a transmission method in which a network’s frequency range is divided into separate channels, each used for transmitting different signals simultaneously.
Browser:
A software type enabling navigation of information databases.
Client:
A computer with access to services over a network. The server provides these services.
DNS:
DNS, or Domain Name Server, is a database translating Internet names to addresses and vice versa.
Document:
In the context of the World Wide Web, a document is any file containing text, media, or hyperlinks transferable from an HTTP server to a client program.
Document Window:
The Mosaic program’s scrollable window where HTML documents can be viewed.
Download:
The act of transferring a copy of a file from another computer to your own.
FAQ:
FAQ stands for Frequently Asked Questions, common files providing answers to frequently posed questions on the Internet.
Firewall:
Security measures protecting a networked system from unauthorized access.
FTP:
FTP, or File Transfer Protocol, is both a protocol enabling file transfer between computers and the act of transferring files.
Gopher:
A menu-oriented tool for locating online resources.
Gopherspace:
The entire gopher network.
GUI:
GUI, or Graphical User Interface, is a software front-end facilitating user interaction with an application.
Home Page:
The initial document displayed when opening Mosaic or the first document at a website.
Hotlists:
Lists of frequently used web locations and URLs.
Host:
A computer serving as an information or communications server.
HTML:
HTML, or HyperText Markup Language, is the language used to tag various parts of a web document for display.
HTML Document:
A document written in HyperText Markup Language.
HTTP:
HTTP, or Hypertext Transfer Protocol, links and transfers hypertext documents.
Hypermedia:
Extending the hypertext concept to include linked multiple media.
Hypertext:
A system enabling cross-linked exploration of documents by clicking on highlighted words or symbols.
IP:
IP, or Internet Protocol, refers to the set of communication standards controlling Internet activity.
ISDN:
ISDN, or Integrated Services Digital Network, is a telecommunications standard supporting voice, video, and data communications over regular telephone lines.
JPEG:
JPEG, or Joint Photographic Experts Group, is an image compression format for transferring color photographs and images over computer networks.
Links:
Hypertext connections between web pages, synonymous with hotlinks or hyperlinks.
POP:
POP, or Point of Presence, is a service provider’s location for connecting to users.
Router:
A communications device transmitting signals via the most efficient route.
Search Engine:
A program helping users find information in text-oriented databases.
Server:
A computer system managing and delivering information for client computers.
TCP-IP:
Basic protocols controlling applications on the Internet.
URL:
URL, or Uniform Resource Locator, is the addressing system used in the World Wide Web.
Web Browser:
Software enabling access and viewing of HTML documents.
Web Document:
An HTML document is browsable on the web.
An HTML document accessible on the web.
The internet has become an indispensable aspect of our daily lives, serving a multitude of purposes. Below are various uses of the internet:
The internet facilitates seamless communication, allowing people to connect effortlessly with individuals residing far away. Beyond simple chatting, video conferencing has become commonplace through platforms like email and social networking sites.
Research has been revolutionized by the internet. Accessing vast amounts of information, previously requiring extensive library visits, is now just a click away. This accessibility not only simplifies the research process but also allows for widespread dissemination of findings.
The internet serves as an invaluable resource for education, offering a plethora of books, reference materials, online help centres, and expert insights. Learning has become more engaging and self-directed, with countless websites covering diverse topics and providing tutorials.
Conducting financial transactions online has streamlined processes, eliminating the need to physically visit a bank branch. Internet-enabled financial transactions enable swift and convenient buying and selling of goods and services.
Internet platforms provide real-time updates across various fields such as business, sports, finance, politics, and entertainment. Decisions are often influenced by the latest happenings worldwide, highlighting the internet’s essential role in staying informed.
Email services, a product of Internet technology, enable instantaneous communication globally. This has revolutionized how individuals connect, fostering global friendships and cultural exploration.
The internet’s most significant advantage is its vast information repository. Anyone can access information on virtually any topic, making it an indispensable tool for acquiring knowledge.
The Internet has catalyzed global trade by facilitating communication and advertising for buyers and sellers. Online classified sites have become popular for cost-effective product and service promotion.
Social networking sites are integral to the online community, serving personal and business purposes. Entrepreneurs use these platforms to build personal and business brands.
Online shopping has gained popularity due to its convenience. Various e-commerce websites offer a wide range of products, and online auctions provide a platform for selling goods.
The internet offers diverse entertainment options, from watching films to playing games online. Music, hobbies, and news can be easily accessed and shared.
E-commerce encompasses a broad spectrum of commercial activities conducted online, ranging from household needs to entertainment products.
Numerous services, such as online banking, job seeking, ticket purchasing, and guidance on various life aspects, are available on the internet, often at lower costs than offline alternatives.
Internet platforms connect employers and job seekers, simplifying the job search process for both parties.
The internet facilitates connections between people, fostering communication and collaboration.
Internet security is a specialized branch of computer security addressing the vulnerabilities associated with online activities. It encompasses browser and network security, employing measures like encryption to safeguard against cyber threats and fraud, such as phishing. The objective is to establish rules and protective measures to counter potential attacks on the internet.
Internet abuse involves the inappropriate use of the Internet and may encompass the following:
The Internet offers numerous benefits when used positively, disregarding deceptive means and alluring charms. False trends, particularly among students, can easily ensnare them with the Internet’s colorful and captivating aspects. Some drawbacks of the Internet include:
A presentation package encompasses various features, including:
The display of the window depends on its size, and resolution determines the amount of information the monitor can show.
The Microsoft Office Button, situated in the upper-left corner, provides options for creating, opening, and saving files.
The Quick Access Toolbar offers convenient access to frequently used commands like save, undo, and redo.
The Title Bar exhibits the name of the active presentation, typically starting with “Presentation1.”
The Ribbon, located near the top, offers a menu with various commands.
Slides, Placeholders, and Notes are central to creating a presentation, with placeholders holding text, clip art, charts, etc., and notes aiding in presentation delivery.
Status Bar, Tabs, and View Buttons facilitate switching between Normal view, Slide Sorter view, and Slide Show view.
The Zoom function allows users to magnify or reduce the window size for focused viewing.
Click the START button, navigate to All Programs, then Microsoft Office, and finally, click Microsoft Office PowerPoint.
Creating a New Presentation:
Organize content on slides using layouts, add effects like themes and backgrounds to enhance presentations.
Inserting Contents:
PowerPoint displays default slides upon opening the package.
To Enter Text:
Click and type the title and subtitle in the designated areas.
To Insert Graphics or Pictures:
Click in the title or subtitle area, press enter, access the insert menu, and choose graphic options like clip art, shapes, or pictures.
To Add Clip Art Object:
Click on clip art, search for desired graphics, and insert the chosen image into the slide.
To Add Picture Object:
Click on the picture button, select the desired image location, and insert it into the slide.
To Choose an Effect:
Select an object, access the animation tab, click custom animation, add an effect from the menu, and apply it.
To Add New Slides:
Choose the Home tab, click New Slide, select a layout, and add text as needed.
To Save a Presentation:
Click the office button, select save, choose the destination, name the document, and click save.
To Run a Slide Show:
Choose the slide show tab, click “From the Beginning,” or the slide show icon for presentation display.
To Print Presentation:
Click the MS Office button, choose print, preview, select print options, and click print.
To Close Presentation:
Click the close button on the title bar.
Website design involves the planning, creation, and ongoing updates of websites. It encompasses elements such as information architecture, website structure, user interface, navigation ergonomics, website layout, colors, contrasts, fonts, photography, and icon design. These elements are combined to form the overall design of websites.
Understanding a web page requires recognizing it as a text file containing HTML formatting tags and links to graphic files and other web pages through a web server. Web pages are distinctive in their interactivity and ability to incorporate multimedia. When creating a web page, it is crucial to establish a goal by incorporating numerous links.
A web design package serves various purposes:
Elements of a Web Design Package
Examples of Web Design Packages
The following are examples of web design packages:
iWeb enables users to effortlessly create websites and blogs, allowing customization with personal text, photos, and videos. Integrating seamlessly with various services like Facebook, YouTube, Google AdSense, and Google Maps, iWeb empowers users to develop a website in minutes without the need for programming or HTML knowledge. The platform provides aesthetically pleasing templates designed by Apple, easily customizable to alleviate design concerns.
Microsoft FrontPage serves as a web tool, providing users the ability to create customized websites without requiring knowledge of HTML code. It facilitates page management and allows users to create and edit web pages in a What-You-See-Is-What-You-Get (WYSIWYG) fashion.
As a versatile web design package, Adobe Dreamweaver accommodates everything from simple page design to the development of dynamic pages using ColdFusion, PHP, ASP, CSS, XML, XSLT, and JavaScript. Recognized as a powerful and feature-rich web development tool, Dreamweaver integrates a robust WYSIWYG editor, FTP client, and a user-friendly scripting environment.
This web design tool facilitates the creation and development of web pages using XML, CSS, ASP.NET, ASP.NET AJAX, XHTML, XSLT, PHP, and JavaScript. Expression Web, requiring .NET Framework and Silverlight for installation and operation, employs its own standards-based rendering engine distinct from Internet Explorer’s Trident engine.
Webplus X4 offers a quick and code-free solution for individuals seeking to create and publish visually appealing desktop and mobile sites.
NetObjects Fusion is a commercial program featuring a graphical user interface that generates HTML or XHTML through its proprietary database.
Amaya stands out as a free and open-source WYSIWYG authoring tool with browsing capabilities. Equipped with XML-based capabilities such as XHTML, MathML, and Scalable Vector Graphics (SVG), Amaya supports free and open image formats like PNG and SVG, including a subset of SVG animation.
Computer graphics refer to visual representations generated using computers, encompassing the creation and manipulation of image data by computational means.
Graphic packages, such as Paint, CorelDraw, Adobe Photoshop, Harvard Graphics, Print Master, Ventura, Photoshop Pro, and Adobe Page Maker, exemplify this digital visual creation and manipulation.
Title Bar:
Displays the name of the active CorelDraw file and facilitates window repositioning.
Menu Bar:
Houses 11 pull-down menus containing all commands.
-Rulers:
Serve as positioning and sizing aids, optionally toggled on or off. Guidelines can be drawn from the rulers for additional assistance.
Scroll Bars:
Enable horizontal and vertical page shifting.
Drawing Windows:
The primary workspace for creating graphics, with the printable page represented by a rectangle with a drop shadow.
Roll-up Window:
Features like the Transform (Position) roll-up, which are not permanently part of the interface, provide quick access for experimenting with CorelDraw operations without navigating through lengthy menu dialog boxes.
Status Bar:
Displays information about the selected object, including fill pattern, outline location, movement, and absolute coordinates.
Colour Palette:
Facilitates the swift application of colored fills or outline colors. An expanded color palette is accessible by selecting the scrollbar at the bottom.
Page Counter:
Indicates the total number of pages in a drawing. Arrows allow navigation between pages.
Standard Toolbar:
Provides quick access to commonly used features, duplicating many found in the Menu Bar. CorelDraw offers customizable toolbars, and keyboard shortcuts such as Ctrl + S (Save), Ctrl + P (Print), Ctrl + Z (Undo), Ctrl + X (Cut), Ctrl + C (Copy), and Ctrl + V (Paste) offer faster alternatives once memorized.
The operational tools include:
The Toolbox:
The toolbox provides a range of operational tools, categorized into:
The Pick Tool
The Shape Tool:
The Zoom Tool:
The Freehand Tool:
Rectangle Tool: Used for drawing rectangles and squares.
Ellipse Tool: Used for drawing ellipses and circles.
The Polygon Tool:
The Text Tool: Used for placing Artistic text and paragraph text.
Interactive Fill Tool:
Interactive Blend Tool: The interactive Blend fly-out gives access to the new distorted tool, Interactive envelop, Extrude, and Drop shadow tools.
Outline Tool:
Fill Tool:
Creating Drawings
Launching the CorelDraw Application
To open the CorelDraw application, follow these steps:
Exiting CorelDraw
To exit the CorelDraw environment, perform the following actions:
Drawing Shapes
Upon launching the application:
Adding Color to Your Shapes
After drawing your shapes:
Converting Your Text to Curve
On the drawing area:
Cleaning the Mouse:
Step 1: Disconnect the mouse cable from the computer case.
Step 2: Lightly dampen a cleaning cloth with isopropyl alcohol, and use it to wipe down the exterior of the computer mouse and mouse pad.
Step 3: Remove the mouse’s bottom cover by turning it over, following the directional arrows indicating the removal direction. Press in the arrow direction, turn the mouse right side up, and let the cover and mouse ball drop into your hand.
Step 4: Clean the mouse ball with a lint-free cloth dampened with isopropyl alcohol and set it aside.
Step 5: Use a swab dampened with isopropyl alcohol to clean between, around, and on top of the keys. Change swabs as needed.
Step 6: Replace the mouse ball and cover.
Step 7: Wipe the mouse cord with a cleaning cloth lightly dampened with a mild soap solution. Gently pull the cord through the cloth.
Step 8: Plug the mouse back into the computer.
Cleaning Your Monitor:
Step 1: Unplug the power supply cord and cable from the monitor, allowing it to cool for at least 20 minutes.
Step 2: Vacuum the monitor’s exterior, paying attention to cooling grooves, holes, or slots. Use compressed air at an angle to remove dust without letting debris fall into ventilation holes.
Step 3: Lightly dampen a cloth with a mild soap solution and wipe down the monitor’s plastic parts.
Step 4: Clean the monitor cables and power cord while disconnected. Gently pull them through a cloth dampened with mild soap solution.
Step 5: Check the monitor for anti-glare or delicate coatings. Follow manufacturer instructions for cleaning. If no special coatings, use a lint-free cloth with window cleaner (sprayed on the cloth, not the screen).
Step 6: In dusty environments, use a computer dust cover to protect the monitor.
Cleaning a Keyboard:
Step 1: Disconnect the cable from the computer case.
Step 2: Use a vacuum cleaner to remove debris between keys or tap the keyboard upside down to dislodge debris.
Step 3: Use compressed air at a 30-45 degree angle between the keys to remove remaining dust. Alternately blow and tap until clean.
Step 4: Lightly dampen a cloth with a mild soap solution and wipe down the keyboard exterior. Avoid spraying directly onto the keyboard.
Step 5: Clean between, around, and on top of the keys with swabs dampened with isopropyl alcohol. Change swabs as needed.
Step 6: Wipe the keyboard cord with a cleaning cloth lightly dampened with mild soap solution. Dry the cord with a dry cloth.
Step 7: In dusty environments, use a keyboard cover for protection.
Charging a Laptop Battery:
Plug your laptop into the socket, and you can leave it there whenever possible. You can recharge your laptop’s battery whether it is fully drained or not. There is no need to fully drain your laptop’s lithium-ion battery every time you use it. Lithium-ion batteries have a rapid-charging option available either on a custom tab inside the Power Option dialog box or through special battery software.
Cleaning a DVD Drive:
Purchase a DVD laser cleaning kit, a single disc designed to spin in your drive and remove dust from the lens. Place the cleaning disc inside your DVD drive’s tray, close it, and let the CD spin to clear the lens of dust. As an extra precaution, open the drive’s disc tray and gently spray a can of air into it to remove any larger pieces of dust.