2.2.15

Structured Query Language

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Structured Query Language

A database is a structured collection of data. Structured query language (SQL) is a language used to query this data.

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SQL

  • SQL is a language that can tell databases what to do.
  • SQL can be used for selecting, inserting, updating, and deleting data.
  • For GCSE you only need to know how to select (search for) data.
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Select statements

  • A SELECT statement searches for and returns data. E.g:
    • SELECT * FROM table_name;
  • The * character tells the database to return all fields.
  • The * character can be replaced by specific fields. E.g:
    • SELECT name FROM users;
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Where clause

  • Sometimes we don't want to return data for all records.
  • We can filter the data using a where clause as follows:
    • SELECT * FROM users WHERE ID=3;
  • The above line would only return a user's data where they have an ID of 3.
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Wildcards

  • Sometimes we don't know the exact value we want to use in a where clause.
  • We can use wildcards to find records which match some sort of pattern.
  • We can use the % symbol to represent anything. For example, if we want to find any names starting with 'Ba' then we could query:
    • SELECT name FROM users WHERE name LIKE "Ba%";

Jump to other topics

1Computer Systems

1.1Systems Architecture

1.1.1Elements of Computer Systems

1.1.2Types of Computer Systems

1.1.3Von Neumann Architecture

1.1.4Registers of the Central Processing Unit (CPU)

1.1.5Fetch-Execute Cycle

1.1.6Factors Affecting CPU Performance

1.1.7Exam-Style Questions - Von Neumann Architecture

1.2Memory & Storage

1.2.1Types of Memory

1.2.2Flash Memory

1.2.3Properties of Flash Memory

1.2.4Running Out of Memory

1.2.5Virtual Memory

1.2.6Exam-Style Questions - Primary Memory

1.2.7Capacity

1.2.8Calculating Capacity Requirements

1.2.9Solid State Storage

1.2.10Properties of Solid State Media

1.2.11Magnetic Storage

1.2.12Properties of Magnetic Media

1.2.13Examples of Magnetic Storage

1.2.14Optical Storage

1.2.15Properties of Optical Media

1.2.16Examples of Optical Storage

1.2.17Types of Optical Disk

1.2.18End of Topic Test - Computer Systems

1.2.19Grade 9 - Storage

1.2.20Exam-Style Questions - Storage

1.2.21Number Bases

1.2.22Converting Number Bases

1.2.23Hexadecimal

1.2.24Using Hexadecimal

1.2.25Binary Addition

1.2.26Binary Shifts

1.2.27Representing Text

1.2.28ASCII & Unicode

1.2.29Representing Images

1.2.30Converting Binary and Images

1.2.31Representing Sound

1.2.32Data Compression

1.2.33End of Topic Test - Representation

1.2.34Exam-Style Questions -Data Conversions

1.3Computer Networks, Connections & Protocols

1.3.1Benefit of Networks

1.3.2Network Performance

1.3.3Networks: How Do Packets Get Routed?

1.3.4Types of Networks

1.3.5Client-Server Model

1.3.6Pros & Cons of Client-Server Model

1.3.7Peer-to-Peer Model

1.3.8Pros & Cons of Peer-to-Peer Model

1.3.9Network Hardware

1.3.10Transmission Media

1.3.11What is the Internet?

1.3.12URLs

1.3.13DNS & Web Hosting

1.3.14The Cloud

1.3.15Pros & Cons of the Cloud

1.3.16Exam-Style Questions - Networking Models

1.3.17Topology

1.3.18WiFi

1.3.19WiFi Frequency and Channels

1.3.20WiFi Encryption

1.3.21IP Addresses

1.3.22MAC Addresses

1.3.23Network Protocols

1.3.24Transmission Protocols

1.3.25Application Protocols

1.3.26Layers

1.3.27Advantages of Layering

1.3.28Exam-Style Questions - Network Protocols

1.4Network Security

1.4.1Forms of Attack

1.4.2Penetration Testing

1.4.3Malware

1.4.4How Malware Spreads

1.4.5Social Engineering

1.4.6Phishing

1.4.7Cracking Passwords

1.4.8Denial of Service Attacks

1.4.9Data Interception

1.4.10Methods of Data Interception

1.4.11SQL Injection

1.4.12Network Administration

1.4.13Network Forensics

1.4.14Protecting Against Malware

1.4.15Firewalls

1.4.16User Access Levels

1.4.17Passwords

1.4.18Encryption

1.4.19End of Topic Test - Networks

1.5Systems Software

1.5.1System Software

1.5.2Utility Software

1.5.3Operating Systems

1.5.4User Interfaces

1.5.5Memory and Process Management

1.5.6File Management

1.5.7Device Management

1.5.8User Management

1.5.9Encryption Software

1.5.10Defragmentation Software

1.5.11Data Compression Software

1.5.12Backup Software

1.6Ethical, Legal, Cultural & Environmental Concern

1.6.1Open Source Software

1.6.2Proprietary Software

1.6.3Licensing Issues

1.6.4Ethical Issues - The Digital Divide

1.6.5Ethical Issues - Net Neutrality

1.6.6Ethical Issues - Working Conditions

1.6.7Ethical Issues - Censorship

1.6.8Exam-Style Questions - Ethical Issues

1.6.9Data Protection Act 1998

1.6.10Computer Misuse Act (1990)

1.6.11Copyright Designs and Patents Act (1988)

1.6.12Creative Commons Licensing

1.6.13Freedom of Information Act (2000)

1.6.14Cultural Issues

1.6.15Environmental Issues

1.6.16Positive Environmental Impact

1.6.17Online Activity Tracking

1.6.18The Internet of Things

1.6.19Stakeholders

1.6.20End of Topic Test - Software & Issues

2Computational Thinking, Algorithms and Programming

2.1Algorithms

2.1.1Computational Thinking - Abstraction

2.1.2Computational Thinking - Decomposition

2.1.3Algorithmic Thinking

2.1.4Pseudocode

2.1.5Flow Diagrams

2.1.6Interpreting Algorithms

2.1.7Correcting Algorithms

2.1.8Completing Algorithms

2.1.9Search Algorithms

2.1.10Linear Search

2.1.11Binary Search

2.1.12Overview of Sort Algorithms

2.1.13Bubble Sort

2.1.14Insertion Sort

2.1.15Merge Sort

2.1.16Exam-Style Questions - Sorting Algorithms

2.2Programming Fundamentals

2.2.1Variable Declaration and Assignment

2.2.2Input and Output

2.2.3Program Flow - Sequence

2.2.4Program Flow - Selection

2.2.5Program Flow - Iteration

2.2.6Arithmetic Operators

2.2.7Relational Operators

2.2.8Boolean Operators

2.2.9Data Types

2.2.10Casting

2.2.11Arrays

2.2.12Strings

2.2.13File Handling

2.2.14Structuring Data - Records

2.2.15Structured Query Language

2.2.16End of Topic Test - Programming

2.2.17Exam-Style Questions - Translation

2.3Producing Robust Programs

2.3.1Defensive Design

2.3.2Validation and Sanitisation

2.3.3Authentication and Contingencies

2.3.4Maintainability

2.3.5Comments

2.3.6Purpose of Testing

2.3.7Types of Testing

2.3.8Test Plans

2.3.9Error Types

2.3.10End of Topic Test - Programming

2.3.11Exam-Style Questions - Testing

2.4Boolean Logic

2.4.1Binary Systems

2.4.2Logic Circuits

2.4.3Boolean Logic

2.4.4Boolean Operators

2.4.5Grade 9 - Logic

2.5Programming Languages & IDEs

2.5.1High-Level vs Low-Level Languages

2.5.2Translation - Compliers & Interpreter

2.5.3Translation - Assemblers

2.5.4Integrated Development Environments

2.5.5Exam-Style Questions - Translation

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Structuring Data - Records

End of Topic Test - Programming