Lesson 5 • Beginner
ORDER BY & Sorting
Sort query results by one or more columns, handle NULL values, and combine sorting with filtering for powerful queries.
🎯 What You'll Learn
- Sort ascending (ASC) and descending (DESC)
- Sort by multiple columns for sub-sorting
- Handle NULL values in sorted results
- Combine WHERE + ORDER BY + LIMIT for real-world queries
Basic Sorting
ORDER BY sorts your results. By default, it sorts in ascending order (A→Z, 1→100, oldest→newest).
📚 Real-World Analogy
ORDER BY is like the "Sort" button on Amazon. Sort by "Price: Low to High" = ORDER BY price ASC. Sort by "Price: High to Low" = ORDER BY price DESC.
Without ORDER BY, SQL returns rows in an undefined order — it could be different every time! Always sort if order matters.
Basic Sorting
Sort results ascending and descending
-- Ascending order (default)
SELECT * FROM products ORDER BY price;
SELECT * FROM products ORDER BY price ASC;
-- Descending order
SELECT * FROM students ORDER BY grade DESC;
-- Sort alphabetically
SELECT first_name, last_name
FROM employees
ORDER BY last_name ASC;Multi-Column Sorting
Sort by multiple columns to create a hierarchy. The second column only matters when the first has ties.
💡 Pro Tip
Each column can have its own sort direction: ORDER BY department ASC, salary DESC groups by department alphabetically, then shows highest salary first within each department.
⚠️ Common Mistake
Sorting by column position (ORDER BY 3) is fragile — if you add a column, the sort changes silently. Always use column names.
Multi-Column & Calculated Sorting
Sort by multiple columns and computed values
-- Sort by department, then salary within each dept
SELECT name, department, salary
FROM employees
ORDER BY department ASC, salary DESC;
-- Sort by calculated value
SELECT product_name, price, price * 0.9 AS sale_price
FROM products
ORDER BY sale_price ASC;
-- Sort by column position (not recommended)
SELECT name, age, grade FROM students
ORDER BY 3 DESC; -- sorts by 3rd column (grade)NULL Handling in Sorting
Control where NULL values appear in sorted results
-- NULL values in sorting
-- NULLs appear first in ASC, last in DESC (varies by DB)
SELECT name, bonus FROM employees
ORDER BY bonus ASC;
-- Force NULLs to the end (PostgreSQL)
-- SELECT name, bonus FROM employees
-- ORDER BY bonus ASC NULLS LAST;
-- Workaround for MySQL: use COALESCE
SELECT name, bonus
FROM employees
ORDER BY COALESCE(bonus, 0) DESC;The Complete Query Pattern
Here's the order SQL clauses must appear in:
SELECT columns FROM table WHERE conditions -- filter rows ORDER BY columns -- sort results LIMIT n OFFSET m; -- paginate
⚠️ Common Mistake
Putting ORDER BY before WHERE. SQL clauses have a strict order: SELECT → FROM → WHERE → ORDER BY → LIMIT.
Real-World Combined Queries
Build production-quality queries combining WHERE, ORDER BY, and LIMIT
-- Combine WHERE + ORDER BY + LIMIT
-- Top 5 most expensive electronics
SELECT product_name, price, rating
FROM products
WHERE category = 'Electronics'
AND rating >= 4.0
ORDER BY price DESC
LIMIT 5;
-- Latest 10 orders from VIP customers
SELECT order_id, customer_name, total, order_date
FROM orders
WHERE customer_type = 'VIP'
ORDER BY order_date DESC
LIMIT 10;
-- Remember: WHERE → ORDER BY → LIMIT
-- This order matters!📘 Quick Reference
| Syntax | Result |
|---|---|
| ORDER BY col | Ascending (default) |
| ORDER BY col DESC | Descending |
| ORDER BY a, b DESC | a ascending, then b descending |
| COALESCE(col, 0) | Replace NULL with 0 for sorting |
| NULLS LAST | NULLs at end (PostgreSQL) |
🎉 Lesson Complete!
You can now sort results in any order and combine sorting with filtering. Next, you'll learn JOIN operations — combining data from multiple tables!
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