regexp_replace()

Replaces the substring that is the first match to the POSIX regular expression pattern, or all such matches if the g flag is used; see Section 9.7.3.

Signature

regexp_replace ( string text, pattern text, replacement text [, flags text ] ) → text
regexp_replace ( string text, pattern text, replacement text, start integer [, N integer [, flags text ] ] ) → text

Examples

SELECT regexp_replace('Thomas', '.[mN]a.', 'M');

ThM

SELECT regexp_replace('Thomas', '.', 'X', 3, 2);

ThoXas

SELECT regexp_replace(string=>'hello world', pattern=>'l', replacement=>'XX', start=>1, "N"=>2);

helXXo world

Run against PostgreSQL 18.6 on 2026-09-13. This is the output we got, not the documentation’s.

In other engines

PostgreSQL	regexp_replace
MySQL	REGEXP_REPLACE(x, p, r) on MySQL 8.0+
SQL Server	no direct equivalent
Oracle	REGEXP_REPLACE(x, p, r)
SQLite	no direct equivalent

SQL Server has no regular expressions in T-SQL before 2025, and SQLite has none without an extension. This is usually the function that decides a piece of logic belongs in the application rather than the query.

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Signature and description adapted from the PostgreSQL manual, used under the PostgreSQL License. PostgreSQL is a registered trademark of the PostgreSQL Community Association of Canada. This page is not affiliated with the PostgreSQL Global Development Group.