⚖️ MySQL Logical & Comparison Operators – Filter, Compare, and Control Data with Precision

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🧲 Introduction – Why Use Logical & Comparison Operators?

In MySQL, retrieving the right data depends on your ability to apply logical and comparison filters. Whether you’re searching for specific values, comparing columns, or building conditional logic, these operators form the foundation of WHERE clauses, JOIN conditions, and control flows.

Used correctly, they empower your SQL queries to become accurate, efficient, and intelligent.

🎯 In this guide, you’ll learn:

• Core logical operators: AND, OR, NOT
• Key comparison operators: =, <>, >, <, BETWEEN, IN, LIKE, IS NULL
• Real-world use cases and query examples
• Best practices for combining conditions and avoiding logic pitfalls

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📘 MySQL Comparison Operators

Operator	Description	Example	Result
=	Equal to	price = 100	True if 100
!= or <>	Not equal to	status <> 'active'	True if not ‘active’
>	Greater than	salary > 50000	True if salary > 50K
<	Less than	age < 30	True if under 30
>=	Greater than or equal	score >= 90	True if 90 or more
<=	Less than or equal	discount <= 10	True if 10 or less
BETWEEN	Within a range (inclusive)	price BETWEEN 100 AND 200	True if within range
IN	Match any in a list	city IN ('NY', 'LA')	True if city is NY or LA
LIKE	Pattern match with wildcard %	name LIKE 'A%'	Names starting with A
IS NULL	Checks for NULL	email IS NULL	True if NULL
IS NOT NULL	Checks not NULL	email IS NOT NULL	True if has value

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🔗 MySQL Logical Operators

Operator	Description	Example	Meaning
AND	Both conditions must be true	salary > 50000 AND dept = 'HR'	Both conditions must match
OR	At least one must be true	status = 'active' OR age < 18	Either condition can match
NOT	Negates a condition	NOT enrolled	True if enrolled is false

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💻 Practical Examples

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1️⃣ Combine Comparison & Logical Operators

SELECT * FROM products
WHERE price BETWEEN 50 AND 200
  AND category = 'Electronics';

🧠 Finds electronics within a price range.

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2️⃣ Use IN with Multiple Options

SELECT * FROM customers
WHERE city IN ('New York', 'Chicago', 'Houston');

💡 Filters based on a list of cities.

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3️⃣ Search with LIKE and Wildcards

SELECT * FROM employees
WHERE name LIKE 'A%';

🧠 Returns all names starting with ‘A’.

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4️⃣ Handle NULL Checks

SELECT * FROM users
WHERE phone IS NULL;

💡 Find users who haven’t provided a phone number.

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5️⃣ Complex Logic with AND & OR

SELECT * FROM orders
WHERE status = 'Processing'
  AND (payment_method = 'Card' OR payment_method = 'UPI');

💡 Use parentheses to group logic correctly.

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📘 Best Practices for Logical & Comparison Operators

✅ Practice	🔍 Tip
Use parentheses for complex logic	Avoids ambiguity in AND/OR precedence
Use IS NULL / IS NOT NULL properly	= NULL will not work—use IS NULL instead
Use BETWEEN for inclusive range	Includes both boundaries (e.g., 10 to 100)
Avoid LIKE '%something' on large sets	Cannot use index efficiently—use full-text search if needed
Use IN over many ORs	Cleaner and may be optimized faster

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🚀 Real-World Use Cases

Use Case	SQL Logic Example
🧾 Filter invoices between dates	invoice_date BETWEEN '2024-01-01' AND '2024-12-31'
🧑‍💼 Segment users by age	age < 18 OR age > 60
📦 Get products in multiple categories	category IN ('Books', 'Toys', 'Games')
📧 Find incomplete signups	email IS NULL OR password IS NULL
🔍 Fuzzy search	name LIKE '%john%'

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📌 Summary – Recap & Next Steps

Logical and comparison operators are the building blocks of filtering and condition handling in MySQL. Used in WHERE, JOIN, HAVING, or CASE expressions, they give your queries powerful control over what data is selected and how it’s analyzed.

🔍 Key Takeaways

• Use comparison operators for direct value checks (=, <>, >, etc.)
• Use logical operators to combine multiple conditions (AND, OR, NOT)
• Use BETWEEN, IN, and LIKE for advanced filtering
• Handle NULLs carefully with IS NULL and IS NOT NULL
• Group conditions properly using parentheses

⚙️ Real-World Relevance

You’ll use these operators in reports, dashboards, access control, analytics, billing, and more—wherever conditional data logic is required.

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❓ FAQ – MySQL Logical & Comparison Operators

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❓ What’s the difference between = and IN?

✅ = compares one value; IN checks if a value matches any value in a list.

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❓ Why doesn’t = NULL work?

❌ Because NULL is not a value—it’s unknown. Use IS NULL or IS NOT NULL instead.

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❓ Is BETWEEN inclusive?

✅ Yes. It includes both lower and upper bounds:

WHERE price BETWEEN 100 AND 200 -- Includes 100 and 200

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❓ What is the precedence of AND and OR?

✅ AND is evaluated before OR. Use parentheses to control evaluation:

-- Correct
WHERE A AND (B OR C)

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❓ Can I combine LIKE with NOT?

✅ Yes:

WHERE name NOT LIKE 'A%';

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