Key term
CCEA A-Level Digital Technology 2650
Systems Analysis and Development Approaches
Topic overviewThe software crisis and the need for systems developmentUser needs, time and costRoles in a systems development teamThe purpose of analysisFact-finding techniquesFunctional and non-functional requirementsData flow diagramsThe waterfall modelRapid application development and AgileResources, constraints and risks in a software projectProject management, Gantt charts and critical path analysisVersion management
Design, Development and Testing
Topic overviewThe purpose of systems designStoryboarding the user interfacePrototyping the interface and the data modelThe development stage: turning a design into working codeWhy testing runs throughout developmentLevels of testing: unit and integrationSystem testingAcceptance testingAlpha and beta testingThe purpose and components of a test planTypes of test data
Implementation and System Security
Topic overviewThe purpose of system implementationDirect and parallel changeoverPilot and phased changeoverUser documentationTechnical documentationData conversionThe purpose of system maintenanceCorrective, adaptive and perfective maintenanceArchiving dataBackup and recoveryFull, differential and incremental backupsDisaster recovery plans
Programming
Topic overviewThe purpose of a computer programThe integrated development environmentTranslation: compilers, interpreters and assemblersThe stages of compilation and linkingAlgorithms, pseudocode and syntaxVariables, constants and data typesSequence and selectionIteration: count-controlled and condition-controlled loopsFlowcharts and algorithm representationObjects, classes and methodsInheritance and evaluating the object-oriented approach
Data, Information and Data Representation
Topic overviewBits, bytes and units of storageHow many values a given number of bits can holdConverting decimal to binaryConverting binary to decimalTwo's complement and negative numbersCharacter sets: ASCII and UnicodeData, information and knowledgeFactors affecting the quality of informationValidation: range, type, length and presence checksValidation: format checks and lookup checksCheck digits and the Modulus 11 methodBatch totals, verification and the limits of checking
Computer Architecture and Processing Systems
Topic overviewThe processor, the clock and the registersThe fetch-execute cycleBuses, input and output controllers and portsMain memory: RAM, ROM and addressingCache memory and the memory hierarchyFactors that affect processing speedThe need for secondary storageMagnetic, optical and flash storage mediaChoosing secondary storage for common applicationsBatch, real-time and transaction processingAutomatic teller machines and point of sale terminalsSmartphones: input, output and processing
System Software, Application Software and the User Interface
Topic overviewUser interfaces: WIMP, command line and forms dialogueChoosing and evaluating a user interfaceInputting text, sound and videoThe purpose of an operating systemHow an operating system manages memory and processesTypes of operating systemUtility programsThe need for data compression, lossless and lossyZipping and archive filesCommon data file formatsApplication software: generic and special purposeObtaining and delivering software
Web Technology and Multimedia
Topic overviewThe internet, the World Wide Web and web standardsURLs, HTTP and the request-response cycleDomain names, DNS and IP addressesWeb browsers, search engines, cache and cookiesWeb servers, hosting, ISPs and file transferIntranets and how an organisation uses oneCreating web pages with HTMLHTML tags for text, lists, images and linksStyling pages with CSSMultimedia assets in a web pageClient-side and server-side processingSecurity over the internet: encryption, HTTPS and certificates
Networks
Topic overviewNetwork scope: LAN, MAN and WANNetwork hardware and connection devicesIP addresses and MAC addressesPeer-to-peer and server-based networksBus, star and ring topologiesThe need for communication protocolsThe OSI seven-layer modelTCP/IP, Ethernet and media access methodsWi-Fi, Bluetooth, VoIP and RFIDBandwidth and broadbandTransmission media: metal cable, fibre optic and wirelessDetecting and correcting transmission errors
Databases
Topic overviewThe relational database and its main featuresLogical and physical data modelsEntities, attributes and keysEntity-relationship modellingNormalisation to third normal formThe data dictionaryStructured Query Language: creating and changing dataStructured Query Language: retrieving dataQuery By Example and alternatives to SQLDatabase security, integrity and recovery
Artificial Intelligence, Expert Systems and Robotics
Topic overviewWhat artificial intelligence meansThe Turing test and machine intelligenceNeural network modellingThe structure of an expert systemThe knowledge base and the inference engineShells, heuristics, fuzzy logic and the knowledge engineerExpert systems in medicine, fault diagnosis and insuranceNatural language processingVoice recognition technologyEvaluating natural language and voice recognition systemsThe technology of roboticsRobotics in commercial situations
Mobile Technology, Data Mining and Cloud Computing
Topic overviewCells, masts and frequency reuseHandoff between cellsThe base station controller, the mobile switching centre and the PSTNWhat data mining isGathering and storing data for miningProcessing and analysing large volumes of dataBig data in health, finance and retailData mining and the privacy of the individualWhat cloud computing isVirtualisation, hosted instances, hosted solutions and clusteringCloud services: storage, email, software and backupEvaluating cloud computing for business
Individual, Social and Legal Considerations
Topic overviewThe Data Protection Act 2018 and the UK GDPRThe data protection principles and the rights of the data subjectThe Copyright, Designs and Patents Act 1988The Computer Misuse Act 1990Data protection duties of an organisationHow the legislation affects employees and the publicThe ethics of automated decision makingOnline censorshipMonitoring of personal behaviourThe ethics of artificial intelligence and of personal information
The Development Project: Analysis and Design
Topic overviewScheduling the project with a Gantt chartInternal and external constraints on the solutionDetailing user requirements as inputs, processes and outputsPrioritising requirements as essential and non-essentialData flow diagrams at level 0 and level 1Specifying hardware and software requirementsThe overall system designProcess descriptions and algorithmsUser interface design and validationData modelling and normalisation for the solutionDesigning the queries and reportsDeveloping a comprehensive test plan
The Development Project: Build, Testing and Evaluation
Topic overviewChoosing software to develop the solutionBuilding the solutionTest data and the types of testingCarrying out and recording the testingDocumenting a strategy for system implementationEvaluating the solution against the user requirementsIdentifying extensions to the systemThe electronic user guideBringing the system into use and supporting itDocumentation for the completed system
Databases
- 10 subtopics
- 30 things to know
- A2 Unit 1
What Databases covers
Databases is examined in Unit A2 1, Information Systems. It covers the relational database and its main features, logical and physical data models, entities, attributes and keys, entity-relationship modelling, normalisation to third normal form, the data dictionary, structured Query Language: creating and changing data, structured Query Language: retrieving data, query By Example and alternatives to SQL and database security, integrity and recovery.
The 10 subtopics
Each one has its own page.
- The relational database and its main featuresRelational database, flat file and database management system.Open →
- Logical and physical data modelsLogical data model, physical data model and conceptual data model.Open →
- Entities, attributes and keysTerm entity, term attribute and term primary key.Open →
- Entity-relationship modellingEntity-relationship model, one-to-one relationship and one-to-many relationship.Open →
- Normalisation to third normal formCharacteristics of data in un-normalised form, characteristics of first normal form and characteristics of second normal form.Open →
- The data dictionaryData dictionary, field length and default value.Open →
- Structured Query Language: creating and changing dataStructured Query Language and data definition language and data manipulation language.Open →
- Structured Query Language: retrieving dataDifference between WHERE and HAVING and difference between an inner join and a left outer join.Open →
- Query By Example and alternatives to SQLQuery By Example, wizard in a database package and stored procedure.Open →
- Database security, integrity and recoveryData integrity, four validation checks a database can apply and check digit.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
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What are the main features of a relational database?
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What is a flat file, and why is it a poor way to store related data?
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Why should a date be stored as a date rather than as text?
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What is meant by an entity occurrence?
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Why can a many-to-many relationship not be implemented directly?
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What is meant by the optionality of a relationship?
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Produce the entity-relationship model for a library that lends copies of books to members.
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Take an Employee table holding employee number, name, department code and department name to third normal form.
Evaluation
What are the disadvantages of normalisation?
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What is a data dictionary?
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Why is a data dictionary useful when a new developer joins a project?
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What does the ORDER BY clause do?
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What is the difference between WHERE and HAVING?
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What is the difference between an inner join and a left outer join?
Evaluation
State two advantages of Query By Example over SQL.
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Why is Query By Example usually specific to one product?
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How do most database products relate Query By Example to SQL?
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What is validation, and what is it able to check?
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What is verification, and how does it differ from validation?
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Name four validation checks a database can apply.
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What is Structured Query Language?
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What is a logical data model?
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Define the term entity.
Numbers
Write the SQL to insert a new member.
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State the difference between a logical and a physical data model.
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Define the term attribute.
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What are the characteristics of data in un-normalised form?
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Why does a data dictionary record validation rules?
Numbers
Write the SQL to change a member's surname.
Take Databases further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Partial dependency vs Transitive dependency
Partial dependency: an attribute determined by part of a composite key. Transitive dependency: an attribute determined by another non-key attribute.
Primary key vs Foreign key
Primary key: an attribute uniquely identifying a record in its own table. Foreign key: an attribute holding a value that identifies a record in a different table.
Questions from this topic
Each one with the model answer underneath.
- 1
What is a relational database?
Model answer
A relational database stores data in tables of rows and columns, where each table holds one kind of thing and tables are joined by shared values rather than by physical pointers. The structure is defined separately from the programs that use it.
- 2
What are the main features of a relational database?
Model answer
A relational database holds data in linked tables, enforces a primary key on every table, links tables through foreign keys, enforces referential integrity, stores each fact once, and is queried through a language such as Structured Query Language rather than by navigating a fixed path.
- 3
What is a flat file, and why is it a poor way to store related data?
Model answer
A flat file stores everything in one table. Related facts then repeat on every row that mentions them, so the same fact is stored many times, storage is wasted, and an update applied to some rows and not others leaves the file contradicting itself.
- 4
What is a database management system?
Model answer
A database management system is the software that sits between users and the stored data, creating and maintaining the structure, enforcing rules and security, and processing queries and updates so that applications do not deal with the files directly.
- 5
What is meant by data independence?
Model answer
Data independence means the structure of the stored data can be changed without rewriting the programs that use it, because applications ask the database management system for data by name rather than reading files in a fixed layout.
- 6
How does a relational database control access to data?
Model answer
A relational database grants privileges to named users or roles, so a user may be permitted to read a table but not to update it, or to see certain columns only through a view that hides the rest.
What is inside Levo
Six ways to work the same material.
Databases revision questions
- What does Databases cover in CCEA A-Level Digital Technology?
- 10 subtopics: the relational database and its main features, logical and physical data models, entities, attributes and keys, entity-relationship modelling, normalisation to third normal form, the data dictionary, structured query language: creating and changing data, structured query language: retrieving data, query by example and alternatives to sql and database security, integrity and recovery. Each one has its own page with questions and model answers.
- How is Databases organised?
- By the CCEA 2650 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Databases, on a schedule.
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