💡 Mastering SQL Comparison Operators: =, !=, >, <, BETWEEN & More Explained Clearly

When working with data in SQL, comparison operators are the building blocks of making decisions and filtering results. They allow you to compare column values against constants, expressions, or other columns—essential for writing meaningful queries.

Whether you’re filtering sales records, user ages, or transaction dates, these operators let you ask precise questions and get relevant answers from your database.

In this guide, we’ll explore the most commonly used SQL comparison operators, how they work, and show you clear examples you can follow—even as a beginner.

🚀 What Are Comparison Operators in SQL?

Comparison operators are used in SQL to compare two values. The result of this comparison is either TRUE or FALSE, which determines whether a particular row should be included in the result set.

These operators are mainly used in:

• WHERE clauses (to filter data)
• JOIN conditions (to connect tables)
• CASE statements (to perform logic)
• HAVING clauses (for filtering grouped data)

🔧 Basic SQL Comparison Operators

Let’s take a look at the most frequently used SQL comparison operators:

🔍 Using the = Operator (Equal To)

The simplest and most used comparison operator.

SELECT *
FROM students
WHERE grade = 'A';

This returns all students who received an A grade.

🔁 Using the != or <> Operator (Not Equal To)

Both symbols work similarly, though <> is ANSI SQL standard and more widely accepted.

SELECT *
FROM users
WHERE status != 'inactive';

This filters out all inactive users.

🔼 Using > and < (Greater Than, Less Than)

You can compare numbers, dates, or even alphabetical values depending on the column type.

Example 1: Numeric

SELECT *
FROM products
WHERE price > 100;

Example 2: Dates

SELECT *
FROM orders
WHERE order_date < '2023-01-01';

This gets orders placed before January 2023.

🔁 Using >= and <= (Greater Than or Equal, Less Than or Equal)

These are often used to include boundary values in your filtering.

SELECT *
FROM exams
WHERE score >= 75;

Shows students who passed the exam with at least 75 marks.

🎯 The Powerful BETWEEN Operator

The BETWEEN operator checks if a value lies within a range of values, inclusive of the boundary numbers.

SELECT *
FROM employees
WHERE age BETWEEN 30 AND 40;

Returns employees aged between 30 and 40.

You can also use BETWEEN with dates:

SELECT *
FROM bookings
WHERE check_in BETWEEN '2024-01-01' AND '2024-12-31';

❗ Using NOT BETWEEN

To filter out values outside a range:

SELECT *
FROM books
WHERE price NOT BETWEEN 10 AND 20;

This fetches all books that cost less than 10 or more than 20.

🔗 Combining Comparison Operators

You can combine multiple comparisons using AND, OR, and NOT.

Example with AND

SELECT *
FROM employees
WHERE department = 'Sales' AND salary > 50000;

Example with OR

SELECT *
FROM products
WHERE category = 'Electronics' OR price < 100;

Example with NOT

SELECT *
FROM users
WHERE NOT age BETWEEN 18 AND 25;

🧠 Real-Life Example: Applying Multiple Comparison Operators

Scenario: A company wants to find customers who:

• Placed an order in 2024
• Ordered more than $500 worth
• Live outside of California

SELECT *
FROM customers
WHERE state != 'CA'
  AND total_spent > 500
  AND order_date BETWEEN '2024-01-01' AND '2024-12-31';

This is a great use of !=, >, and BETWEEN in a single query.

🧩 Comparison Operators with Strings

SQL also allows comparisons between string values. Keep in mind, strings are compared alphabetically (lexicographically).

SELECT *
FROM cities
WHERE city_name > 'M';

This returns cities that come after M alphabetically.

📝 Notes on NULLs and Comparisons

SQL uses a special keyword NULL to represent missing values. Comparing NULL using = or != won’t work.

-- Wrong
WHERE email = NULL

-- Correct
WHERE email IS NULL

🧼 Best Practices

• Always quote string values with 'single quotes'.
• Avoid != NULL — use IS NOT NULL.
• Use parentheses for clarity when combining multiple conditions.
• Know your data types—comparing numbers and strings can lead to unexpected results.
• Use BETWEEN when you’re working with ranges—it makes your query more readable and efficient.

❓ Why Should Beginners Learn These Operators First?

Comparison operators are used in nearly every SQL query beyond the most basic ones. Whether you’re filtering data, analyzing performance, or extracting trends, you’ll need these operators.

Understanding them helps you:

• Build complex queries
• Make decisions with CASE or IF
• Perform better data analysis
• Combine conditions logically

🏁 Conclusion

SQL comparison operators like =, !=, >, <, BETWEEN, and others form the foundation of data filtering. They’re not just tools—they are your language for asking smart questions of your data.

The more you use them, the more natural they become. Try them out in your own database projects or with practice tools like SQL Fiddle or SQLite online. And remember, clear logic makes for clean data!