📝 What You’ll Learn

  • What the AND operator does
  • Syntax and logic
  • Combining multiple conditions
  • Real-world examples
  • Common mistakes

🔍 What Is the AND Operator?

The AND operator is used in SQL to combine multiple conditions in a WHERE clause. All conditions joined by AND must be true for a row to be included in the result.

🧱 Basic Syntax

SELECT column1, column2
FROM table_name
WHERE condition1 AND condition2;

This means:

Only return rows where both condition1 and condition2 are true.

🔄 Example: Filtering with AND

Suppose we have a table employees with columns: name, age, department.

SELECT name
FROM employees
WHERE age > 30 AND department = 'Sales';

✅ This query returns employees who are over 30 and work in the Sales department.

⚙️ More Examples

Find users from USA who are active

SELECT name
FROM users
WHERE country = 'USA' AND status = 'active';

Get products in stock and under $50

SELECT product_name, price
FROM products
WHERE stock > 0 AND price < 50;

🧠 Common Mistakes

  • ❌ Forgetting parentheses when mixing AND with OR:

    -- Can lead to unexpected results:
SELECT * FROM users WHERE country = 'USA' OR country = 'UK' AND active = 1;

-- ✅ Better:
SELECT * FROM users WHERE (country = 'USA' OR country = 'UK') AND active = 1;

  • ❌ Using AND when you meant OR, or vice versa — read your logic carefully!

📘 Recap

  • AND combines multiple conditions and all must be true
  • Helps you write precise and powerful filters
  • Use parentheses when combining with OR for clarity
  • Always test your conditions for accuracy