Lesson Notes By Weeks and Term v5 - Grade 12

Lesson Video

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Performance objectives

• Demonstrate proficiency in SQL database design and queries.
• Apply object-oriented programming (OOP) principles in Java.
• Analyse different network topologies and protocols.
• Apply knowledge of SDLC methodologies.
• Evaluate ethical considerations and cybersecurity risks.

Lesson summary

This week's focus is on comprehensive revision and targeted examination preparation. We'll be revisiting crucial concepts from the term, strengthening understanding, and refining exam-taking strategies. This is particularly important as IT skills are increasingly vital in South Africa's rapidly digitizing economy. Whether you aspire to be a software developer, web designer, data analyst, or simply a tech-savvy citizen, a solid foundation in IT will be invaluable.

Lesson notes

This week focuses on the consolidation and application of key IT concepts. We'll be primarily revising the following areas: Databases (SQL), Object-Oriented Programming (Java), Networking and SDLC. 2.1 Databases (SQL) SQL (Structured Query Language) is essential for managing and manipulating data in relational database management systems (RDBMS). Understanding SQL is crucial for IT professionals in South Africa, as businesses and government entities rely heavily on databases to store and process information.

Key Concepts: Database Design: Understanding entity-relationship diagrams (ERDs) and how they translate to relational database schemas with tables, primary keys, and foreign keys. Normalization is key to reduce data redundancy and improve data integrity.

SQL Statements: `SELECT`, `INSERT`, `UPDATE`, `DELETE` statements for CRUD (Create, Read, Update, Delete) operations.

Joins: Combining data from multiple tables using `INNER JOIN`, `LEFT JOIN`, `RIGHT JOIN`, and `FULL OUTER JOIN`. Understand when to use each type of join.

Subqueries: Using queries within queries to filter data or perform calculations.

Aggregate Functions: `COUNT()`, `SUM()`, `AVG()`, `MIN()`, `MAX()` for performing calculations on groups of data.

GROUP BY and HAVING Clauses: Grouping data based on specific criteria and filtering groups based on aggregate function results.

Worked example

Assume we have two tables: `Customers` (CustomerID, Name, City) and `Orders` (OrderID, CustomerID, OrderDate).

Question: Write an SQL query to retrieve the name of each customer and the number of orders they placed, only for customers who have placed more than 2 orders and are located in Cape Town.

Solution:

```sql

SELECT Customers.Name, COUNT(Orders.OrderID) AS NumberOfOrders

FROM Customers

INNER JOIN Orders ON Customers.CustomerID = Orders.CustomerID

WHERE Customers.City = 'Cape Town'

GROUP BY Customers.Name

HAVING COUNT(Orders.OrderID) > 2;

```