Flags and tools Updated November 2026

Regex in SQL

Regex in SQL depends on the database. PostgreSQL uses ~ (and ~* for case-insensitive) plus regexp_replace, regexp_matches and substring(col from pattern). MySQL 8 and MariaDB use REGEXP or RLIKE with REGEXP_REPLACE and REGEXP_SUBSTR. Oracle has REGEXP_LIKE. SQL Server has no regex before SQL Server 2025 and Azure SQL, which add REGEXP_LIKE.

Syntax

PostgreSQL: col ~ 'pattern'      MySQL: col REGEXP 'pattern'      Oracle: REGEXP_LIKE(col, 'pattern')      BigQuery: REGEXP_CONTAINS(col, r'pattern')

Examples

-- PostgreSQL
SELECT email FROM users WHERE email ~* '^[^\s@]+@[^\s@]+\.[^\s@]+$';

Result: rows whose email has the usual shape, matched case-insensitively

-- MySQL 8
SELECT phone FROM contacts WHERE phone REGEXP '^[0-9]{3}-[0-9]{3}-[0-9]{4}$';

Result: rows like 555-123-4567

-- PostgreSQL
SELECT regexp_replace('a  b   c', '\s+', ' ', 'g');

Result: a b c

The 'g' flag replaces every run; without it only the first.

-- MySQL 8 / Oracle
SELECT REGEXP_SUBSTR('Order #4521', '[0-9]+');

Result: 4521

Common mistakes

Doubling nothing in MySQL: in a MySQL string literal, backslashes must be escaped, so write '\\d' or use [0-9], which works everywhere.
Forgetting the 'g' flag in PostgreSQL regexp_replace, which replaces only the first match.
Using LIKE as if it were regex; LIKE only has % and _ wildcards.
Ignoring case rules: MySQL REGEXP follows the column collation (often case-insensitive), PostgreSQL ~ is case-sensitive unless you use ~*, Oracle REGEXP_LIKE takes an 'i' match parameter.

Practice Regex in SQL

These drills check your answer on live data, free, no account needed.

Simple email addressesThe whole line must match. Use this simplified rule: a local part of letters, digits, dots, underscores, plus signs or hyphens; one @; one or more domain labels of letters, digits or hyphens separated by dots; and a final label of two or more letters.
Keep only the digitsRemove every character that is not a digit, so phone numbers in any format become plain digits.
US phone number formatsThe whole line must match. Accept (555) 123-4567, or ten digits split 3, 3 and 4 by the same separator throughout: a hyphen, a dot, or nothing.

Questions

How do I use regex in SQL Server?

SQL Server 2025 and Azure SQL Database add REGEXP_LIKE, REGEXP_REPLACE, REGEXP_SUBSTR and related functions. On earlier versions use LIKE with character ranges, PATINDEX, or a CLR function.

What are the regex functions in BigQuery?

REGEXP_CONTAINS(text, pattern) for a boolean, REGEXP_EXTRACT(text, pattern) for the first match or group, REGEXP_EXTRACT_ALL for an array, and REGEXP_REPLACE. BigQuery uses the RE2 flavor, so no lookarounds or backreferences.

Does SQLite support regex?

SQLite defines the REGEXP operator but ships no implementation; it works only if the host application registers a regexp() function (Python's sqlite3 can with create_function). Otherwise use LIKE or GLOB.

Regex in ExcelThe native regex functions in Microsoft 365 Excel to test, extract and replace text, the return_mode and case options, Google Sheets equivalents, and VBA.
Regex in Python (re)How the Python re module works: search versus match versus fullmatch, findall and its group behavior, sub for replacement, raw strings, and flags.
Regex for emailA practical email regex for JavaScript and other engines, how to validate a whole field, extract addresses from text, and why RFC-perfect patterns are a trap.
Regex for numbers onlyThe ^\d+$ pattern for digits-only strings, stripping everything that is not a digit, extracting numbers from text, and patterns for signed and decimal values.