Aggregate Functions & Grouping - Concepts

Introduction to Aggregate Functions & Grouping

Key Concepts

• Understanding the core principles of aggregate functions & grouping
• Practical applications and real-world use cases
• Step-by-step implementation guides
• Common patterns and best practices
• Tips for debugging and troubleshooting
• Performance optimization techniques

Aggregate Functions & Grouping - Code Example

-- Aggregate Functions
SELECT 
  department,
  COUNT(*) AS employee_count,
  AVG(salary) AS avg_salary,
  MAX(salary) AS max_salary,
  MIN(salary) AS min_salary,
  SUM(salary) AS total_salary
FROM employees
GROUP BY department
HAVING COUNT(*) > 5
ORDER BY avg_salary DESC;

-- GROUP BY with multiple columns
SELECT department, job_title, COUNT(*) AS count
FROM employees
GROUP BY department, job_title;

Try It Yourself: Aggregate Functions & Grouping

-- Try aggregate queries!
SELECT 
  category,
  COUNT(*) AS product_count,
  ROUND(AVG(price), 2) AS avg_price,
  MAX(price) AS most_expensive
FROM products
GROUP BY category
HAVING AVG(price) > 25
ORDER BY avg_price DESC;

Quick Quiz: Aggregate Functions & Grouping