Mastering SQL: Practical Database Design and Query Examples
SQL Database Management: Supplier and Product Inventory
Defining the Inventory Schema (DDL)
We begin by setting up the database structure for tracking suppliers and their products. Note the use of PRIMARY KEY, FOREIGN KEY, and CHECK constraints for ensuring data integrity.
Supplier Table Creation
CREATE TABLE Supplier (
SupplierID INT PRIMARY KEY,
Name VARCHAR(100) NOT NULL,
City VARCHAR(50)
);Product Table Creation
CREATE TABLE Product (
ProductID INT PRIMARY KEY,
Name VARCHAR(100)Fundamentals of Software Development, Testing, and Modeling
What is Software and Its Common Myths?
Definition of Software
Software is a set of instructions, data, or programs used to operate computers and execute specific tasks. It is the intangible component of computers, as opposed to hardware.
Types of Software
- System Software: e.g., Operating Systems
- Application Software: e.g., MS Word, Web Browsers
- Programming Software: e.g., Compilers, Editors
Common Software Myths
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Core Software Engineering Concepts
Software Engineering
Read MoreEconometric Methods for Establishing Causality
1. RCTs Versus Quasi-Experimental Methods
A randomized controlled trial bakes causality into the data: random assignment severs every systematic link between treatment status and unobserved factors. Consequently, the simple difference in average outcomes is unbiased, provided compliance and sample integrity hold. The four quasi-experimental tools imitate this causal magic only by leaning on single-point assumptions:
- Ordinary Least Squares (OLS): Assumes no omitted variable is correlated with the regressor.
Software Maintenance, Evolution, and Documentation Best Practices
Software Maintenance Fundamentals (Week 1)
Definition of Software Maintenance (SM)
- “The modification to a software product after delivery to correct faults.”
Maintenance vs. Software Evolution
| Maintenance | Evolution |
|---|---|
| All activities preventing failure or decay of a software system. | Activities that provide new or changed functionality only. |
Software Aging and Decay
- Software ages when it does not adapt to changing technology, user needs, or competitors.
Lehman’s Laws of Software Evolution
- Continuing Change:
- Real-
Aggregate Supply, Demand, and Economic Growth Factors
Aggregate Supply and Demand Dynamics
Short-Run and Long-Run Aggregate Supply
Determinants of Short-Run Aggregate Supply (SRAS)
What are the determinants of short-run aggregate supply? Changes in input prices, taxes, and business and inflationary expectations.
Determinant of Aggregate Supply (AS)
What is a key determinant of aggregate supply? Productivity.
SRAS Curve Slope
The short-run aggregate supply curve slopes upward because profits increase at high price levels and because many input prices are slow
African History: Empires, Trade Routes, and Cultural Shifts
Key Concepts in African History
- Almoravids & Songhai: Successive empires in West Africa.
- Ahmadu Bamba & Muridism: The founder of the Murid Sufi brotherhood.
- Berbers: Indigenous peoples of North Africa, masters of the desert.
- Swahili Coast: A center of the Indian Ocean trade network.
- Great Zimbabwe: A powerful medieval Southern African civilization.
- Sundiata & Balla Fasséké: The founder of the Mali Empire and his griot.
- Mansa Musa & Mali: The renowned emperor of the Mali Empire.
Islam’s
Read MoreGlobal Political Systems: Six Case Studies
British Political Traditions and Constitution
Introduction: Britain, officially known as the United Kingdom (UK), is a strong and historic union of four countries: England, Scotland, Wales, and Northern Ireland. Its constitution is unwritten, based on traditions and historical documents, allowing it to be easily adapted over time. Having once ruled a vast empire—where it was famously said, “The sun never sets on it”—Britain still plays an influential role in global politics, trade, and diplomacy.
Read MoreGlobal Food Production and Spain’s Primary Sector Challenges
State of the Fishery Sector Globally
Fishing refers to the capture of aquatic animals, algae, and plants in seas, rivers, and lakes.
Global Fish Consumption Trends
In an earlier period, an average of 9 kg of fish per person per year was consumed, while in 2020, this figure reached 20 kg.
- China is the country with the greatest fishery production and the main fish exporter.
Aquaculture: Breeding Aquatic Life
Aquaculture is the breeding of aquatic animals and plants in captivity. In 2020, 46% of global fish
Read MoreSpanish Urban System: Hierarchy and Major Development Axes
There is genuine competition for it. In the case of Spain, in 1992, this competition was highlighted by the hosting of the **Olympics** and the **World Exposition** (Seville).
Hierarchy and Urban Networks in Spain
The Spanish urban system has a hierarchical urban network typical of a developed country. A city’s importance is determined by the size of the area it influences (its **hinterland**). The size of the hinterland depends on the range and quantity of services the central city can offer. The
Read MoreEnglish Verb Forms: Future Tenses and Modals
Future Forms
Will / Won’t + Infinitive
- Use: Predictions, promises, quick decisions (spontaneous decisions).
Shall (I / We)
- Use: Suggestions or offers (often in question form).
(To be) Going to + Verb
- Use: Plans, intentions.
Present Continuous
- Use: Fixed arrangements (plans that are certain to happen).
- Example: I’m working tonight.
Present Simple
- Use: Timetables, schedules, dates.
- Example: The train leaves at 9 p.m.
- Negative: The train doesn’t leave until 9 p.m.
- Question: What time does the train leave?