MySQL REGEXP, RLIKE, and NOT REGEXP – Advanced Pattern Matching Explained

Introduction – What Is REGEXP in MySQL?

MySQL’s REGEXP operator allows for regular expression-based pattern matching, providing far more flexibility than LIKE. It’s used for:

• Validating text formats
• Advanced searching (e.g., ranges, character classes)
• Filtering text that does not match a pattern using NOT REGEXP

In this guide, you’ll learn:

• How to use REGEXP, RLIKE, and NOT REGEXP
• Syntax and supported regular expression features
• Real-world examples
• Tips and performance notes

1. REGEXP – Match Using Regular Expressions

Syntax

SELECT * FROM table_name WHERE column REGEXP 'pattern';

Returns rows where column matches the regex pattern.

Example – Names Starting with A or B

SELECT name FROM employees WHERE name REGEXP '^[AB]';

Matches: Alice, Ben
Skips: Charlie, David

2. RLIKE – Synonym for REGEXP

SELECT name FROM employees WHERE name RLIKE 'son$';

Equivalent to REGEXP 'son$'
Use either—they behave exactly the same.

3. NOT REGEXP – Invert Match Logic

SELECT name FROM customers WHERE email NOT REGEXP '@gmail\\.com$';

Returns customers whose emails do not end with @gmail.com.

4. Common REGEXP Patterns in MySQL

Escaping Special Characters

Use \\ to escape regex meta characters:

SELECT email FROM users WHERE email REGEXP '\\.edu$';

Matches emails ending with .edu

5. Case Sensitivity in REGEXP

• REGEXP is case-insensitive by default in MySQL:

SELECT 'apple' REGEXP 'A'; -- Returns 1 (match)

• Use BINARY for case-sensitive regex:

SELECT name FROM clients WHERE BINARY name REGEXP '^A';

Matches only names starting with uppercase A

6. REGEXP Use Cases

REGEXP vs LIKE – Key Differences

Performance Tips

• Avoid using REGEXP on large datasets unless absolutely needed
• Prefer indexed LIKE 'prefix%' queries for performance
• Test regex patterns thoroughly before production usage
• Use REGEXP with filtered subsets (WHERE type = 'email' AND ...)

Summary – Recap & Next Steps

MySQL’s REGEXP, RLIKE, and NOT REGEXP provide powerful pattern-matching capabilities that go far beyond LIKE. Use them when you need flexible validation, complex filtering, or character-level matching.

Key Takeaways

• Use REGEXP or RLIKE for regular expression matching
• Use NOT REGEXP to find rows that do not match a pattern
• Escape characters carefully (e.g., \\. for .)
• REGEXP is case-insensitive unless BINARY is used
• Ideal for validating formats, filtering by patterns, and advanced searches

FAQ – REGEXP / RLIKE / NOT REGEXP

Are REGEXP and RLIKE the same?

Yes. RLIKE is an alias for REGEXP.

Can I use REGEXP in WHERE clause?

Yes. It’s designed for pattern matching in WHERE.

Is REGEXP case-sensitive?

No, by default. Use BINARY for case-sensitive matching.

Can I use multiple regex conditions?

Yes, using alternation or AND/OR:

REGEXP 'foo|bar' -- matches either

Is REGEXP slower than LIKE?

Yes. REGEXP cannot use indexes, so it’s slower on large tables.