SQL & Databases Masterclass Course
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SQL Review: Simple SELECT Queries
Introduction & Core Concept
You have mastered the foundational building blocks of SQL querying: column projection (SELECT), table selection (FROM), logical filtering (WHERE), sorting (ORDER BY), and bounding output slices (LIMIT).
Now, it's time to test your ability to combine all these clauses into a single, cohesive business inquiry.
Strict Compiler Keyword Order
When writing queries, you must arrange your clauses in this exact chronological order:
1. SELECT (Target columns & aliases)
2. FROM (Target table)
3. WHERE (Filtering constraints)
4. ORDER BY (Sorting instructions)
5. LIMIT (Row count boundaries)
Why & Where We Use It
Real-World Example
A warehouse manager needs a restock list of all 'Home & Kitchen' or 'Accessories' products that retail for less than $100, sorted by their remaining stock levels so the lowest stock items appear at the very top.
Best Practices: What to Do & What NOT to Do
AND and OR operators inside your WHERE filter, always use explicit parentheses to separate logical groupings.ORDER BY clause before WHERE. The compiler will immediately throw a syntax parsing error!Syntax & Pro Tips
SELECT name, category, price, stock
FROM products
WHERE (category = 'Home & Kitchen' OR category = 'Accessories')
AND price < 100.00
ORDER BY stock ASC;