🔁 MySQL Logical Operators (AND, OR, NOT) – Combine Conditions in SQL

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🧲 Introduction – Why Learn Logical Operators in MySQL?

In real-world SQL queries, filtering data using just one condition isn’t always enough. That’s where logical operators like AND, OR, and NOT come into play. These operators let you build complex and powerful WHERE clauses by combining multiple conditions for accurate data filtering in MySQL.

🎯 In this tutorial, you’ll learn:

• What AND, OR, and NOT do in SQL
• How to combine multiple conditions in MySQL
• Use cases where logical operators simplify queries
• Examples for each operator in various scenarios

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📘 What Are Logical Operators in MySQL?

Logical operators are used to combine multiple Boolean conditions in SQL queries, especially within the WHERE clause. MySQL supports:

Operator	Description
AND	Returns true if both conditions are true
OR	Returns true if any one condition is true
NOT	Reverses the result of a condition

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🧪 Examples of MySQL Logical Operators

🔹 1. Using AND – All Conditions Must Be True

SELECT * FROM employees
WHERE department = 'Sales' AND experience > 3;

📌 Returns employees in Sales department and with more than 3 years of experience.

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🔹 2. Using OR – At Least One Condition Must Be True

SELECT * FROM customers
WHERE city = 'Delhi' OR city = 'Mumbai';

📌 Returns customers who live in either Delhi or Mumbai.

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🔹 3. Using NOT – Negate a Condition

SELECT * FROM users
WHERE NOT status = 'inactive';

📌 Returns users whose status is not inactive.

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🔹 4. Combine AND with OR

SELECT * FROM products
WHERE category = 'Electronics'
AND (brand = 'Sony' OR brand = 'Samsung');

📌 Returns electronic products where brand is either Sony or Samsung.

📘 Note: Use parentheses () to group conditions and control evaluation order.

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⚙️ Evaluation Order: AND vs OR

• AND has higher precedence than OR
• Always use parentheses to avoid unexpected results

❌ Without Parentheses (Risky)

SELECT * FROM orders
WHERE status = 'paid' AND method = 'card' OR method = 'upi';

This may return unintended results.

✅ With Parentheses (Safe)

SELECT * FROM orders
WHERE status = 'paid' AND (method = 'card' OR method = 'upi');

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🔍 Real-World Use Cases

Scenario	SQL Example
🔐 Authenticate users with multiple rules	SELECT * FROM users WHERE email='john@example.com' AND password='abc123';
📍 Find users from select cities	SELECT * FROM users WHERE city='Delhi' OR city='Bangalore';
🧾 Exclude specific values	SELECT * FROM orders WHERE NOT status = 'cancelled';
💰 Complex promotions or discounts	SELECT * FROM orders WHERE amount > 500 AND (coupon='YES' OR vip='Y');

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📌 Summary – Recap & Next Steps

Logical operators allow SQL queries to become flexible and intelligent. They help filter records with precision when dealing with multiple conditions in MySQL.

🔍 Key Takeaways

• AND returns true only when all conditions are true
• OR returns true when any one condition is true
• NOT inverts the condition’s result
• Parentheses ensure proper logic grouping in complex queries

⚙️ Real-World Relevance

From building login systems to generating filtered reports and business rules, logical operators are foundational tools in every MySQL-powered app.

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❓ FAQ – MySQL Logical Operators

❓ Can I use multiple AND and OR in one query?

✅ Yes. Use parentheses to group them logically:

SELECT * FROM products
WHERE stock > 0 AND (category = 'Books' OR category = 'Stationery');

❓ What is the precedence of AND and OR?

✅ AND has higher precedence than OR. Always use parentheses when combining them.

❓ How do I use NOT with IN?

SELECT * FROM employees
WHERE department NOT IN ('HR', 'Finance');

❓ Can I use logical operators in UPDATE and DELETE?

✅ Yes, any SQL statement with a WHERE clause can use logical operators.

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