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MySQL REGEXP Function



The MySQL REGEXP function is used to perform regular expression matching. It returns 1 if the expression matches the regular expression specified by pattern, else returns 0. If expression or pattern is NULL, the return value will be NULL.

The REGEXP function performs a case-insensitive match, except when used with binary strings.

The REGEXP function is a synonym for the RLIKE function.

Syntax

expression REGEXP pattern

Parameters

expression Required. Specify a character expression such as a column or field.
pattern Required. Specify the regular expression matching information. See the table below for pattern syntax.

Regular Expression Patterns

SymbolDescription
^Matches the beginning of a string.
$Matches the end of a string.
*Matches zero or more occurrences.
+Matches one or more occurrences.
?Matches zero or one occurrence.
.Matches any character except NULL.
|Used like an "OR" to specify more than one alternative.
[ ]Matches any single character specified within [].
[^ ]Matches any single character that is not specified within [].
-Represents a range of characters.
( )Used to group expressions as a subexpression.
{m}Matches m times.
{m,}Matches at least m times.
{m,n}Matches at least m times, but no more than n times.
\nn is a number between 1 and 9. Matches the nth subexpression found within ( ) before encountering \n.
\dMatches a digit character.
\DMatches a nondigit character.
\wMatches a word character.
\WMatches a nonword character.
\sMatches a whitespace character.
\Smatches a non-whitespace character.
*?Matches the preceding pattern zero or more occurrences.
+?Matches the preceding pattern one or more occurrences.
??Matches the preceding pattern zero or one occurrence.
{n}?Matches the preceding pattern n times.
{n,}?Matches the preceding pattern at least n times.
{n,m}?Matches the preceding pattern at least n times, but not more than m times.
[..]Matches one collation element that can be more than one character.
[=character_class=]Represents an equivalence class. It matches all characters with the same collation value, including itself.
[:character_class:]Represents a character class that matches all characters belonging to that class.

List of standard class name

Character Class NameMeaning
alnumAlphanumeric characters
alphaAlphabetic characters
blankWhitespace characters
cntrlControl characters
digitDigit characters
graphGraphic characters
lowerLowercase alphabetic characters
printGraphic or space characters
punctPunctuation characters
spaceSpace, tab, newline, and carriage return
upperUppercase alphabetic characters
xdigitHexadecimal digit characters


Example: Match on more than one alternative

Consider a table called Employee. The below query is used to fetch all records from this table where Name contains either "Ja", "Je" or "Ji". To specify more than one alternative for the second character of the pattern, | is used.

SELECT * FROM Employee
WHERE Name REGEXP 'J(a|e|i)';


Example: Match on Beginning

Consider a table called Employee. The below query is used to fetch all records from this table where Name starts with "J". Here, ^ is used to specify starting character of the pattern.

SELECT * FROM Employee
WHERE Name REGEXP '^J';


Example: Match on End

Consider a table called Employee. The below query is used to fetch all records from this table where Name ends with "n". Here, $ is used to specify end character of the pattern.

SELECT * FROM Employee
WHERE Name REGEXP 'n$';


Example: Matching List

Consider a table called Employee. The below query is used to fetch all records from this table where Name contains either "Ja", "Jb", "Jc" or "Jd". To specify the second character of the pattern, [  ] is used, which can be either "a", "b", "c" or "d" in this case.

SELECT * FROM Employee
WHERE Name REGEXP 'J[a-d]';


Example: Non-Matching List

Consider a table called Employee. The below query is used to fetch all records from this table where Name does not contain either "Ja", "Jb", "Jc" or "Jd". The [ ^ ] pattern is used to specify characters which are not listed here.

SELECT * FROM Employee
WHERE Name REGEXP 'J[^a-d]';


Example: Match Character Class

Consider a table called Employee. The below query is used to fetch all records from this table where Address contains a pattern which starts with 123 and then the remainder of the characters are alphanumeric characters.

SELECT * FROM Employee
WHERE Address REGEXP '123[[:alnum:]]*';


Example: Escaping Characters

To escape special characters when using the REGEXP function, the special character should be preceded with two backslashes \\. Consider a table called Employee. The below query can be used to fetch all records of this table where Address contains a ( character.

SELECT * FROM Employee
WHERE Address REGEXP '\\(';

❮ MySQL - REGEXP

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