> For the complete documentation index, see [llms.txt](https://mariadb.com/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mariadb.com/docs/server/reference/sql-functions/string-functions/regular-expressions-functions.md).

# Regular Expressions Functions

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[Regular Expressions Overview](/docs/server/reference/sql-functions/string-functions/regular-expressions-functions/regular-expressions-overview.md)
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Get an overview of regex usage. This page introduces the pattern matching capabilities and common metacharacters used in MariaDB regular expressions.
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[PCRE - Perl Compatible Regular Expressions](/docs/server/reference/sql-functions/string-functions/regular-expressions-functions/pcre.md)
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Understand MariaDB's regex support. This concept page explains the PCRE library integration, detailing supported syntax, character classes, and special characters.
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[REGEXP](/docs/server/reference/sql-functions/string-functions/regular-expressions-functions/regexp.md)
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Complete REGEXP operator reference: expr REGEXP/RLIKE pat syntax, 1/0/NULL return values, NOT REGEXP aliases, BINARY case-sensitivity, default\_regex\_flags.
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[NOT REGEXP](/docs/server/reference/sql-functions/string-functions/not-regexp.md)
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Negated regular expression matching. This operator tests whether a string does NOT match a specified regular expression pattern.
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[REGEXP\_INSTR](/docs/server/reference/sql-functions/string-functions/regular-expressions-functions/regexp_instr.md)
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Return the index of a regex match. This function finds the starting position of the first substring that matches the given pattern.
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[REGEXP\_REPLACE](/docs/server/reference/sql-functions/string-functions/regular-expressions-functions/regexp_replace.md)
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Replace regex matches in a string. This function substitutes occurrences of a pattern with a specified replacement string.
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[REGEXP\_SUBSTR](/docs/server/reference/sql-functions/string-functions/regular-expressions-functions/regexp_substr.md)
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Return the substring matching a regex. This function extracts the actual part of the string that matches the given pattern.
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[RLIKE](/docs/server/reference/sql-functions/string-functions/regular-expressions-functions/rlike.md)
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Synonym for REGEXP. This operator performs a regular expression match against a string argument.
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