On this Padlet- You will be able to access many things to help you learn here. This includes-

• LAA Theory Section

• LAB Theory Section

• LAC Theory Section

• Past Papers

• Annotated Past Papers with answers

• Revision Workbook

• Revision Theory Book

• Link to all Know it All Ninja Videos

• Email- Short for electronic mail, this lets us send written messages instantly to the other side of the world using the internet. This is much quicker than using traditional mail.

• Instant messaging- This allows us to have private written conversations with an individual or group of people. It’s a great way of organizing a meeting with a group of friends and is cheaper than a phone call.

• News groups- These are similar to modern-day Internet forums and are used to discuss topics and share ideas.

  Unlike instant messaging, newsgroups are public. Anyone accessing the newsgroup can read the messages that have been posted.

• Social networking- Websites like Twitter or Facebook allow us to share our thoughts, opinions, and pictures quickly with all of our friends and family. 

  This helps us keep in touch with our wider friendship groups, whom we might otherwise lose contact with.

• Web conferencing- Software like Skype allows us to talk with people via voice or video call, so you can see them as you’re talking.

• Blogs- Short for Web Logs, these are web pages that are regularly updated and typically used as a public online journal.

Common types of real-time information services include:

• Train timetables- These are used to look up the departure and arrival times of trains so we can plan our journeys, ensure we are on time, and check for train delays.

• News services- Keep us informed about the latest events. The BBC news website, for example, has the latest news stories on a variety of topics.

• Traffic reports- Information on traffic, such as road accidents or congestion, is now often integrated into route-planning websites like Google Maps, which highlights heavy congestion in red when you plan a route.

• Flight status updates- Identify flight arrival times, delays, etc. If you are picking someone up from the airport, you want to know if their flight has been delayed so you don’t arrive too early.

• Weather reports- Weather updates and forecasts for the week ahead so that we can plan outdoor events.

Common types of commerce services include:

• Online banking- Check how much money you have, pay people, or transfer money into different accounts, such as to a friend or to your savings. 

  This is quicker and easier than banking in person and is available 24/7.

• Auction sites- Websites like eBay allow us to sell things we own to other people directly. People bid on your item, such as a jumper, and whoever bids the highest gets it.

• Retail sales- These are websites that allow us to do all our regular shopping online. We can buy our groceries, clothes, electrical equipment, and anything else online from the same stores you might visit. 

  It’s also common for many shops to only sell online, like Amazon.

• Electronic publishing- Produce digital publications such as books and magazines so you can buy them online and instantly download them to your computer, tablet, smartphone, or specialist e-reader like the Amazon Kindle.

Common types of government services include:

• Online tax returns- You can complete tax returns online to ensure you’ve paid the right amount of tax to the government.  This is quicker, easier, and can check for mistakes automatically, which makes it beneficial to traditional paper-based tax returns.

• E-voting- We can cast our votes in elections without having to visit polling stations. This allows people who live in remote areas or have mobility issues to cast their votes without difficulty.

• Online application for grants and benefits- Housing benefits, car tax, or TV licenses can be applied for online instead of at council offices, post offices, etc. This saves a lot of time, both in travelling and in avoiding long queues.

Education is a big growth area in online services. It concerns the use of the Internet for learning and training.

This could be used for distance learning degrees, exam preparation, or health and safety training for a new job.

There are more online education websites appearing all the time; you’re using an online education service right now, KnowItAll Ninja!

Common types of communication services include:

• Online learning websites- Helps students study for particular courses or learn new skills, such as studying for their GCSE exams. It can also be used for other things, such as distance learning, to gain professional qualifications or a degree.

• Online training services- Learn work-based skills, such as induction training for a new job or completing specific work-based tasks correctly. This can be more cost-effective for a business than having its own internal training and also allows you to work at your own pace.

Virtual Learning Environments

Virtual learning environments, often called VLEs, are another category of online service. A VLE provides a virtual classroom online that lets teachers and their students communicate and share resources. Your school or college likely uses a VLE, the most popular being Moodle & Google Classroom.

Business Services

Common types of business services include:

• Video conferencing- This lets us organise and run meetings with people based all around the world without having to travel.

• Collaborative working- Work together on a document with multiple other people at the same time. We often use this alongside video conferencing so we can talk while working on the same document.

• Online business networks- Make connections with people working in the same industry and find new clients by communicating with them and sharing ideas over the Internet.

Entertainment Services

Common types of entertainment services include:

• Online multi-user games- These are extremely popular, such as online first-person shooters and role-playing games. Games such as Fortnite are popular online and are played by millions of people.

• Online radio players- Along with music and video streaming services, this allows us to listen to the latest music and TV shows from wherever we are. Services like Apple Music & Spotify are examples of this.

Download Services

Common types of download services include:

• Music & film downloading- Services like iTunes allow you to purchase music & films and download them to your device, which could be your PC, tablet, or smartphone.

• Software & games downloading- This is also growing in popularity now that superfast broadband connections are more readily available. Steam is a service that allows you to buy and download PC games.

• Software upgrades- These can be downloaded to ensure you are running the latest version of the software and that any security issues are fixed quickly.

Online Advertising

Online advertising is a means of promoting products and services using the internet.  It can be used to spread marketing messages widely to customers.  Online data storage is another example of an online service

Online advertising uses a number of methods to promote products and services.  The most commonly used methods include:

●      Search engine results pages.  Companies can register with the bigger search engines (Google, Bing, Yahoo!) so that their websites appear high up in a list of keyword searches or pay for links that appear when a user does a search.

●      Banner and pop-up advertisements.  These are advertisements that appear at the top of web pages or pop up on web pages.  These are often animated to capture attention.

●      Email marketing.  Users email to send advertisements to customers (both potential customers and existing customers).  However, customers often see this type of marketing as spam if it is sent as unsolicited bulk emails..

Online advertising is becoming a very popular means of promoting products and events, but it isn’t always effective.  To ensure that online advertising is effective, companies need to make sure that it:

1. Captures the attention of the target market using design features (colour, layout, graphics, animation, for example in a banner advertisement) and is easily accessible.

2. Retains consumers’ interest, for example by directing consumers to additional interactive information about a product, such as a video demonstration of the product.  The speed with which the information loads is also important to make sure that consumers don’t lose interest.

Pay-per-click advertising

Pay-per-click (PPC) advertising is a form of online advertising.  It involves websites or web pages hosting ads for other companies.  If a surfer clicks on an ad, they will be redirected to the advertiser’s website.  The website or web page provider will receive a payment for every ad that is clicked on.

Pay per click advertising uses what is known as an affiliate model.  Advertisements or links to a company’s website are placed on other websites (affiliates) and in return the affiliate site receives a percentage of the income from any customer that clicks through Google, AdWords, Yahoo! Search Marketing and Microsoft adCenter are all big players in this field.

Data backup is a method of making copies of files.  These copies can then be retrieved if disaster recovery is needed.

Online Documents

Online documents (such as text documents, spreadsheets, presentations, graphics and forms) are any documents that are held on a computer but can be accessed, edited and shared from anywhere.  Services which allow this include Live Documents, Microsoft Office Live and Google Docs.

Compressing files

Working with online documents means that local files frequently need to be uploaded for sharing or downloaded to be used for local processing.  Files may be extremely large, which can cause problems with transmission (delivery) in terms of speed and network usage.  To reduce this problem, files have to be compressed (i.e. reduced in size )  before transmission and then expanded after transmission.  A common method of doing this is to convert them to zip file (zip format).

Zip files are basically stores of data files which may have been compressed.  There are many different algorithms for doing the compression – with most compression software supporting several of these.  The last item in a zip file is an index, which shows the placement of each of the data files and allows other files to be added.  Quite often the zip file will contain some program code (a sequence of instructions) to allow the files within the zip file to be unzipped (known as self-extracting files).

There is a wide range of software available for zipping files – one of the most popular of these is WinZip.

The Advantages of Using Online Software

The biggest advantage of using online document software is that you can allow many people to share a version of a document and work on it at the same time as other people (known as collaborative working).  You can also access content:

●      Anywhere there is an available internet connection

●      Via different devices (e.g. PC, smartphone, tablet)

●      On different operating devices(e.g. Windows and Mac)

Online documents can also have automatic backup.  Backing up files means that you save a copy of the file at a known point in time.  This means that you save a copy of the file at a known point in time.  This means that you can always go back to that version if you lose or corrupt the present version.

Some software programs will automatically make a copy of the file you have open and are working on at set time intervals.  In Microsoft Word you can set how often you would like the file to automatically backup (every 30 minutes, every 60 minutes, etc.)  Automatic backup of online documents is just an extension of this concept. 

Other methods of version control include the software allocating the latest version number, showing the time and identity of the person making the changes.  If, for any reason, a document does become corrupt (damaged) or is missing important updates, it is possible to roll back to a commonly agreed version number.

Levels of access and files permissions

The system administrator within an organisation can control the levels of access users have to a particular document.  They can allocate access to individuals or particular groups of documents by using file permissions.  Some users may only be able to read documents, but not edit them.  Other users may be allowed to read and edit documents, some may be allowed to add new documents and some will be allowed to delete documents.

●      Read only access – this allows a user to look at and read a document, but not to change it.  A university lecturer could use a word document to create a test for their class.  If he set the document as ‘read-only, then the class will not be able to make any changes to the work.

●      Read/write access – this allows a user to look at and read a document, but also to make changes to it.

●      Full control – this allows users to retrieve a document, read it, edit it, add a new document or delete or archive an existing document.  Full control is usually given to people who administer the system.  They may be senior people within the organisation or senior administrators who report directly to senior management.

Implications of Online Communication

Social Networking

Social networking websites have changed the way that we communicate.  They allow people to communicate interactively in real-time anywhere in the world.  Groups of like-minded people can share information, opinions and interests cheaply, normally for the cost of a broadband connection.  Social networking provides a great way of staying in touch with friends and business contacts.

Instant Messaging

Instant messaging provides a way to exchange textual messages as an alternative to the telephone and at a fraction of the cost.  As messages are sent in real time, responses can be received instantaneously.

However, instant messaging does have its disadvantages:

●      Emotions are better expressed in person and can sometimes be miscommunicated within an instant message that is sent quickly.

●      Viruses can be spread by instant messaging.

Being able to contact relatives and business colleagues on the other side of the world at relatively low cost is the biggest benefit.  VoIP software is often used by businesses for online conferences and meetings.  This reduces travel costs, travel time (and therefore loss of productivity while travelling) and the cost of hiring a venue.

As with all new technology, VoIP has its limitations:

●      Reliability – VoIP service is dependent on the quality and reliability of your broadband service and may not work if there is a power cut.

●      Voice quality – Voices can sometimes be distorted or there may be long pauses between questions and answers.

●      Security – as with all internet technologies, identity theft, viruses, spamming and phising are all potential threats.

Ubiquitous computing, or ‘the internet of objects’, describes how computers are embedded into all sorts of objects we use in our daily lives, such as cars, kitchen appliances and even clothes.

Cloud Computing and Cloud Storage

Cloud computing means using computer services on another organisation’s computers, which are known as hosts.  The services are  provided by organisations known as hosting companies.

Some well-known hosting companies for cloud computing include Amazon, Microsoft, Google an RackSpace.  Cloud users can access software, data and storage on the host computers, which will be at a remote location.  Users do this through a web browser or mobile app, without ever directly accessing the servers that the information is stored on.

Cloud storage is related to cloud computing – it is where only the storage, access and retrieval facilities are provided by the host provider, often via the internet.

Radio frequency identification (RFID)

Currently, objects within a ubiquitous computing environment usually contain radio frequency identification (RFID) chips.  RFID is a technology that uses radio waves to transfer data to a tag on a person or an object so that the person/object can be identified and tracked.  These tags contain information that is stored electronically and can be transmitted.  It is similar to the bar code systems used in supermarket, but unlike a bar code, RFID does not need to be scanned.  An example of how RFID is used is the cat flaps that only open for the animal that has the correct chip in its collar.

Applications of ubiquitous computing

Currently, there are computer systems in place that monitor shelf and warehouse stock.  This technology is used by many industries (supermarkets, book and DVD suppliers, car part manufacturers, etc).  When the stock reaches a certain minimum level, an order is automatically placed with the appropriate supplier electronically.  This is usually done by a process in which the tills feed product sales to a central computer, which then calculates the present stock.  Currently, manual checks still have to be made to allow for ‘shrinkage’ (loss due to theft or damage).

However, there are now experimental systems involving products that contain RFID.  The RFIDs register when any product leaves the premises.

Some futuristic examples of ubiquitous computing include:

●      A car that can inform the owner when it needs service, book itself into the garage and place orders for any parts needed

●      A refrigerator that can monitor its contents, compile an order as food is used and add the items to the user’s online shopping account.

Malware- Malicious Software. These are small programs that are designed to attack computer systems. There are several different types of malware, for example:

• Viruses

• Spyware

• Worms

• Trojans

Phishing- This is a very common threat that occurs from the use of email. This is where you receive an email that claims to be from a legitimate business or website but is actually from a malicious internet user. Example-

1. You receive an email that looks like it is from your bank, which asks you to log into your online bank account.

2. The email will contain a link that, when you click on it, takes you to a website that looks like your bank’s website.

3. If you enter your online banking login details, then all that data will be sent to the malicious user.

• Passwords- Contain more than 8 characters, special characters

• Levels of access- If someone doesn’t need access to a particular system, folder or file, then set their access rights so they cannot access it.

• Firewalls- This is a software program that monitors all connections to your computer and the data that is transferring into and from your computer through those connections.

• Anti-virus- This is a software program that is designed to prevent viruses and other malware from infecting your computer before they can cause damage.

• Encryption- With encryption, we turn our data into another form, called ciphertext, that cannot be understood without being decrypted. E-commerce websites often use encryption to keep your data secure when you enter it on a web form.

• Monitoring technology- This can include things like CCTV & GPS trackers for monitoring their location, as well as keyloggers, email monitoring and screen-capturing software for monitoring communications.

Backup & Recovery- There are many different types of backup, for example:

• Full backup- This is where all files and folders on a hard disk are backed up. Each time the backup is run, a new complete copy of all the files and folders is taken.

• Incremental backup- This is where only files and folders that are new or have changed since the last backup was run are backed up.

• Differential backup- This is where only files and folders that are new or have changed since the last FULL backup was run are backed up.

We commonly back up our files to a USB storage device or an external hard disk.

However, it is becoming much more common to back up our data to cloud storage on the Internet.This gives the added security of keeping it offsite, and you don’t need to worry about possibly losing or damaging the USB device or external hard disk.

• This is why it is so important to be aware of what you are posting on social media and what others are posting about you.

• To protect your e-reputation when using social media, you should always ensure correct security/privacy settings are in place and make sure images can only be seen by friends

Legislation- Legislation has been passed to ensure that our personal data is kept safe. Some of this is to force organisations to better protect our data from threats, and some of it is to punish the people who steal or damage our data. The two major laws that are involved with this are the:

• Data Protection Act- is a law that protects individuals’ personal data from misuse. This law defines 7 principles that organisations must abide by when they handle an individual’s data.

• Computer Misuse Act- Computer misuse is made illegal by the Computer Misuse Act 1990. This law identifies four different computer misuse offences that can be punished.

  • Offence 1 – Unauthorised access to computer material.

  • Offence 2 – Unauthorised access with intent to commit or facilitate the commission of further offences.

  • Offence 3 – Unauthorised acts with intent to impair, or with recklessness as to impairing, the operation of a computer.

  • Offence 3a – Making, supplying or obtaining anything which can be used in computer misuse offences.

To achieve this feat, the Internet relies on several hardware devices that make up the core of its physical infrastructure. These devices include:

• Clients- Your PC, laptop, mobile phone, or tablet is considered a client.

• Servers- There are a number of different types of servers, including file servers, print servers, web servers & email servers.

• Networks- The internet itself is a network of networks, all interconnected together.

• Routers-Its job is to direct data along the correct “route” when these networks meet to ensure the data will successfully reach its destination along the fastest path possible.

• Connecting Backbones-The biggest example of this is the “Internet Backbone”, which is made up of super fast network lines run by a number of large companies and makes up the principal route to send data across the internet.

Internet Service Providers (ISP)

An ISP is a company that provides home and business customers with access to the internet, normally for a monthly fee. Essentially the ISP is connecting you to the internet backbone. Other than internet access, the ISP will often provide a number of additional services, such as:

• Email- You can normally set up an email address provided by your ISP. For example, if your ISP is BT, you might have an @btinternet.com email address.

• Web hosting space- Often, web hosting space is provided, allowing you to put your own website onto the internet.

• Online support- This can come in the form of webpage tutorials, FAQs, email support and instant messaging.

Point of Presence (POP)

Points of Presence, or PoP for short, are access points to the internet. It is a physical location that contains all the hardware required to connect to the internet, such as servers, routers & modems.

A large Internet Service Provider, such as BT, will normally have several PoPs to ensure they can supply good access to the internet so that users can connect to the ISPs network and to the internet backbone.

Network Access Points (NAPs)

A Network Access Point, or NAP, is a place where different ISPs can connect and exchange data between their networks.

The internet is made up of thousands of individual networks. No one actually owns the Internet, and there is no overall controlling network. So, these individual networks need to be able to connect and share data.

That is the role of the NAPs, and in this way, all of the computers on the internet are connected to each other.

Connection Methods & Protocols

There are three main methods that we can use to connect to the internet.

• Wireless Connections- These are any method of connecting to the internet without wires. Advantages include- use it anywhere there is WIFI, Disadvantage- Less secure

• Broadband Connections- These are wired connections to a broadband supplier. Advantages include- faster connection. Disadvantages- Move as far as the cable can go.

• Dial-up connections- These are wired connections that run via a traditional telephone line. Advantages- Available in places where broadband may not be. Disadvantages- Much slower.

Bandwidth & Transmission Rate

We measure this by bandwidth and transmission rate.

The bandwidth of a connection method measures the maximum capacity of a network in bits per second.

So, with your internet connection, if you have a bandwidth of 24Mb, then you can transfer 24Mb of data per second.

The transmission rate refers to the actual amount of data that has been transferred across the network in a specified period of time. Again, this is normally measured in bits per second.

Internet Protocols

There are three core protocols that are absolutely fundamental to the Internet, which are:

• Transmission Control Protocol (TCP)- checks for errors in the data packets and requests any that have errors to be resent.

• Internet Protocol (IP)- he IP will identify the IP address for the packets of data and direct them to the recipient over the internet.

• File Transfer Protocol (FTP)- This protocol allows us to transfer files between two computers across a TCP-based network, such as the Internet.

A website is a group of interconnected web pages.

Interconnected” means individual web pages that are all linked together. These links are created by hyperlinks.

This web address is known as the Uniform Resource Locator or URL. URLs are made up of several different components:

• The Protocol- The protocol we use with web pages is the Hypertext Transfer Protocol, or HTTP for short.

• The Domain Name- The name of our website, specifying a particular web server on the internet. For example, www.knowitallninja.com.

• The File Path- The file location on the server for the specific web page we want to view. Sometimes, we just enter the domain name without a path. This will open the homepage, which is normally named index.html.

Search Engines

The process of using a search engine is as follows:

1. You enter a description (known as the keywords) of what you are looking for in the search field and press enter.

2. Your keywords are searched against the search engine index to find matching web pages.

3. It will then display a list of the best matching web pages, ordered by their popularity, along with a short description of the web page’s content.

Examples of search modifiers include:

• Exact match- This returns only pages that meet the exact phrase that is between the quotation marks. (e.g. “KnowItAll Ninja”).

• Query exclusion- This excludes any results that use the keyword with the minus symbol attached to it. (e.g. KnowItAll -Ninja).

• Query combiner- This returns search results that contain both keywords. (e.g. KnowItAll AND Ninja)

HTML Elements

The TABLE tag adds a table to our webpage. All table tags must have <tr> and <td> tags inside them to create the rows and cells. The <tr> tag adds a table to a row, and the <td> tag adds a cell to a row. TD stands for Table Data.

<table>

<tr>

<td>Some Data</td>

</tr>

</table>

In simple terms, the process can be described as:

1. Open the email client

2. Send to the outgoing mail server

3. Store in recipient’s mailbox

4. Log in and download

Advantages of email:

• Mass communication

• Address book

• Sending files & images

• Speed

• Accessibility

Disadvantages of email:

• Malware

• Phishing

• Spam

• Imperfect Filters

Packet switching is a method of data exchange over a network. With packet switching, data is broken down into a number of parts known as packets.

Header

• Source Address – The IP address of where the data was sent from.

• Destination Address – The IP address where the data is being sent so that each packet knows exactly where it is being transferred to.

• Protocol – This defines what type of packet is being transmitted, e.g. HTML file or email.

• Packet ID –  The unique identifier of the packet, which is used to help reassemble the data correctly when it reaches the destination.

Packet Contents

Payload

• Coded Data – The actual piece of the overall data that we are sending in the packet that can then be reassembled with the other packets at the destination

Trailer

• Error Control Bits – This checks that the packets have been reassembled correctly.

  
  

Transmission Modes

The three types of transmission modes are:

• Simplex- Data can be sent only through one direction, from the transmitter to the receiver. We cannot send a message back to the sender.

• Half-duplex- Data can be sent in both directions, but only one at a time. So, when someone sends data, we cannot send it back until they’re finished.

• Full-duplex- Data can be sent in both directions simultaneously. So, both devices communicating can send and receive data at the same time.

Parallel & serial transmission

As well as the direction of data exchanges, we can also classify different transmission modes by how much data they can transfer simultaneously.

In this way, we can have:

• Serial transmission- Bits of data are sent one at a time over a single wire or channel.

• Parallel transmission- Allows us to send several bits of data simultaneously over an equal number of wires or channels.

Wired & Wireless Methods

Wired

When it comes to data transfer, there are two real categories: wired & wireless.

Wired data transfer involves the physical connection of devices using methods like:

• Fibre optic cables- This uses glass or plastic fibres to transmit data.

• UTP/STP- This stands for Unshielded Twisted Pair and Shielded Twisted Pair, respectively. Both cables are made up of pairs of copper wires twisted together.

Wireless

Common methods include:

• Infrared – This uses infrared light to carry data between devices.

• Microwave – This uses small wavelength, high-frequency radio signals, called microwaves, unsurprisingly, to transmit data.

• Satellite – This uses satellites in space to transmit data between different points on Earth. The data is transferred to the satellite and then relayed back down to the receiver.

Some of these key components include:

• Routers- It serves as the central hub that manages network traffic between your local network and the internet.

• Access points- Access Points (APs) are devices that create a wireless local area network (WLAN) within a larger wired network.

• Wireless network adapters- Wireless network adapters are hardware devices that enable devices that don’t have built-in wireless capabilities to connect to a Wi-Fi network.

  
  

VOIP

In terms of hardware, beyond your basic need for a computing device such as a PC with a monitor, you do need a couple of additional input and output devices, including:

• Microphone- This is a device that simply allows users to input audio, such as their voice, into a computer system.

• Webcam- A webcam is a video camera that can feed the images it is recording to a computer in real-time.

• Speakers/Headphone- These are devices that will output audio in sound waves.

VoIP software like Skype and FaceTime is the major type of software we use for real-time online voice and video conversations.

These can be used for web conferencing, but there are software applications specifically designed for this, for example, Zoom.

Client Vs Server Side

Client-Side Processing

As mentioned, client-side processing is where data is processed on the user’s computer.

Small programs written in a client-side language, like JavaScript, are downloaded to your computer, compiled and run.

Client-side processing is used commonly in web pages for things like:

• Rollover effects- This is where you move your mouse over a section of a web page, such as an image.

• Validating forms- Web pages often have forms (such as a contact or login form)

• Cookies- These are small text files that are stored on your computer and can be used for things like keeping you logged into a website

Advantages of client side:

• Faster

• More secure

Disadvantages of client side:

• Browser Specific

• Speed of processing

  
  

Server Side

Server-side processing is commonly used in web pages when a user submits a form for things like:

• User profile login- With server-side processing, we can access a database of usernames and passwords that are stored on the server.

• Search engines- Similarly, we can look up a database of web pages and match it against search terms entered by a user.

• E-Commerce sites- Online shops have large databases of products and so when you load the page of a particular item, all the details (such as price, description, reviews) are loaded from the database and displayed to you.

• Message boards- Sites like Reddit, or any online forum, store people’s posts in a database using server-side processing and load and display the posts to others.

Advantages of Server Side:

• Speed

• Easy to update

• Browser Independence

Disadvantages of Server Side:

• Security

• Overloading

To understand the structure of a database, we need to know a few important terms:

• Tables- Most of us know what a table is from using spreadsheet software. It is a grid made up of rows and columns.

• Records- A row in a table. A record holds all the data on a single item.

• Fields- An individual piece of data in a record.

Database

Some of the common data types include:

• Text- Stores alphanumeric values.

• Number- Stores numerical values.

• Date/time- Stores date and time values.

• Boolean- Stores a logical value of True or False

Relational Databases

There are two main types of databases. These are:

Flat-File – All data is stored in a single table.

Relational – Data is split across several tables that are linked together using relationships.

Most professional databases are relational.

This is because there are several key advantages to using a relational database. These include:

• Reduced data duplication- Because data is stored in different tables, we can reduce data duplication.

• Efficient searching- Data in a relational database is more organised, quicker and more efficient to search for specific information.

• Less human error- Due to the reduction in data duplication, we have to type less when entering data and so are less like to make a mistake.

Within a database, these tables are linked together with what is called relationships.

To understand how we make relationships between tables, you must first understand the terms “primary key“ and “foreign key”.

Primary- The primary key is a field that is always unique. For example, a staff id number.

Foreign- To create a relationship between two tables, we simply take the primary key field from one table and then repeat it in the table we want to create the relationship in.

Online Databases

An online database is a database that is accessible over a network such as the internet.

Examples of online database software include Microsoft Access (as long as you are using a Sharepoint server), Caspio and QuickBase. There are many reasons that online databases are used, such as:

• Library Catalogues

• Legal History

• Music

• Comic Books

The DBMS (as we often refer to it as) acts as an interface between the user and the underlying data.

Some of its major functions are to allow us to:

• Define & modify the database structure

• Manage access to the data

• Search & sort the data

• Insert & update the data

It has two main parts:

Data Definition Language

Known as DDL for short, it allows us to define our database structure, such as the tables, fields & primary keys.

Data Manipulation Language

Known as DML for short, it allows us to manage our data, such as to insert, update & delete data or search for some specific data.