Regexp_replace mysql

Regexp_replace mysql DEFAULT

Database.Guide

In MySQL, the function replaces occurrences of the substring within a string that matches the given regular expression pattern.

The whole string is returned along with the replacements.

If there’s no match (i.e. the input string doesn’t contain the substring), the the whole string is returned unchanged.

Syntax

The syntax goes like this:

REGEXP_REPLACE(expr, pat, repl[, pos[, occurrence[, match_type]]])

Where is the input string and is the regular expression pattern for the substring. The argument is the replacement string.

The optional argument allows you to specify a position within the string to start the search. If omitted, it starts at position 1.

The optional argument allows you to specify which occurrence of the match to search for. If omitted, all occurrences are replaced.

The optional argument is a string that specifies how to perform matching. This allows you to refine the regular expression. For example, you can use this argument to specify case-sensitive matching or not.

Example 1 – Basic Usage

Here’s a basic example:

SET @str = 'It was good'; SELECT @str 'Original String', REGEXP_REPLACE(@str, 'good', 'great!') 'Result';

Result:

+-----------------+---------------+ | Original String | Result | +-----------------+---------------+ | It was good | It was great! | +-----------------+---------------+

In this case there’s a match, and the string is returned with the modification.

Example 2 – Multiple Matches

By default, if there are multiple matches within the string, all of them are replaced:

SET @str = 'Cat Dog Cat Dog Cat'; SELECT @str 'Original String', REGEXP_REPLACE(@str, 'Cat', 'Tiger') 'Result';

Result:

+---------------------+---------------------------+ | Original String | Result | +---------------------+---------------------------+ | Cat Dog Cat Dog Cat | Tiger Dog Tiger Dog Tiger | +---------------------+---------------------------+

However, you also have the option of specifying which occurrence you’d like to replace (more on this later).

Example 3 – No Match

Here’s an example where there’s no match:

SET @str = 'Cat Dog Cat Dog Cat'; SELECT @str 'Original String', REGEXP_REPLACE(@str, 'Cow', 'Tiger') 'Result';

Result:

+---------------------+---------------------+ | Original String | Result | +---------------------+---------------------+ | Cat Dog Cat Dog Cat | Cat Dog Cat Dog Cat | +---------------------+---------------------+

There’s no match, so the string is returned unchanged.

Example 4 – The Argument

Here’s an example of specifying the starting position:

SET @str = 'Cat Dog Cat Dog Cat'; SELECT @str 'Original String', REGEXP_REPLACE(@str, 'Cat', 'Tiger', 2) 'Result';

Result:

+---------------------+-------------------------+ | Original String | Result | +---------------------+-------------------------+ | Cat Dog Cat Dog Cat | Cat Dog Tiger Dog Tiger | +---------------------+-------------------------+

We started at position 2, which comes after the start of the first occurrence, so the replace operation only affects those occurrences that come after the first one.

Example 5 – The Argument

As mentioned, by default, all occurrences are replaced. However, you also have the option of specifying a specific occurrence to replace by using the argument. Here’s an example:

SET @str = 'Cat Dog Cat Dog Cat'; SELECT @str 'Original String', REGEXP_REPLACE(@str, 'Cat', 'Tiger', 1, 2) 'Result';

Result:

+---------------------+-----------------------+ | Original String | Result | +---------------------+-----------------------+ | Cat Dog Cat Dog Cat | Cat Dog Tiger Dog Cat | +---------------------+-----------------------+

In this case we start at position 1. However, if we start at a different position, the result is different:

SET @str = 'Cat Dog Cat Dog Cat'; SELECT @str 'Original String', REGEXP_REPLACE(@str, 'Cat', 'Tiger', 2, 2) 'Result';

Result:

+---------------------+-----------------------+ | Original String | Result | +---------------------+-----------------------+ | Cat Dog Cat Dog Cat | Cat Dog Cat Dog Tiger | +---------------------+-----------------------+

This happened because our starting position came after the first occurrence had started. Therefore, occurrence 2 became occurrence 1, and occurrence 3 became occurrence 2.

The default value for the occurrence argument is , which means all occurrences are replaced. In other words, if you omit this argument, all occurrences are replaced (as we’ve seen in the previous examples). Here’s an example of explicitly specifying all occurrences:

SET @str = 'Cat Dog Cat Dog Cat'; SELECT @str 'Original String', REGEXP_REPLACE(@str, 'Cat', 'Tiger', 1, 0) 'Result';

Result:

+---------------------+---------------------------+ | Original String | Result | +---------------------+---------------------------+ | Cat Dog Cat Dog Cat | Tiger Dog Tiger Dog Tiger | +---------------------+---------------------------+

Example 6 – The Argument

You can provide an additional argument to determine the match type. This allows you to specify things like whether or not the match is case-sensitive, whether or not to include line terminators, etc.

Here’s an example of specifying a case-sensitive match and a case-insensitive match:

SET @str = 'Cat Dog Cat Dog Cat'; SELECT @str 'Original String', REGEXP_REPLACE(@str, 'cat', 'Tiger', 1, 0, 'c') 'Case-Sensitive', REGEXP_REPLACE(@str, 'cat', 'Tiger', 1, 0, 'i') 'Case-Insensitive';

Result:

+---------------------+---------------------+---------------------------+ | Original String | Case-Sensitive | Case-Insensitive | +---------------------+---------------------+---------------------------+ | Cat Dog Cat Dog Cat | Cat Dog Cat Dog Cat | Tiger Dog Tiger Dog Tiger | +---------------------+---------------------+---------------------------+

The argument can contain the following characters:

Case sensitive matching.
Case insensitive matching.
Multiple-line mode. Recognize line terminators within the string. The default behavior is to match line terminators only at the start and end of the string expression.
The character matches line terminators. The default is for matching to stop at the end of a line.
Unix-only line endings. Only the newline character is recognized as a line ending by the , , and match operators.

MySQLfunctions, regex, string functions

Sours: https://database.guide/how-the-regex_replace-function-works-in-mysql/

bludnic/regexp_replace.sql

/* SELECT test */SELECT ID, reg_replace(post_content, '<aside class="mashsb-container(.*)">((.|\n)*)<\/aside>', '', TRUE, 2, 0) as contentFROM wp_postsWHERE post_content REGEXP('<aside class="mashsb-container(.*)">((.|\n)*)<\/aside>')LIMIT1/* Update */UPDATE wp_postsSET post_content = REGEXP_REPLACE('post_content', '<aside class="mashsb-container(.*)">((.|\n)*)<\/aside>', '')WHERE ID =469/* Function https://stackoverflow.com/questions/986826/how-to-do-a-regular-expression-replace-in-mysql/986870#986870*/DROPFUNCTION IF EXISTS reg_replace;DELIMITER //CREATEFUNCTIONreg_replace(subject VARCHAR(21845), pattern VARCHAR(21845), replacement VARCHAR(21845), greedy BOOLEAN, minMatchLen INT, maxMatchLen INT)RETURNS VARCHAR(21845) DETERMINISTIC BEGIN DECLARE result, subStr, usePattern VARCHAR(21845); DECLARE startPos, prevStartPos, startInc, len, lenInc INT; IF subject REGEXP pattern THENSET result ='';-- Sanitize input parameter valuesSET minMatchLen = IF(minMatchLen <1, 1, minMatchLen);SET maxMatchLen = IF(maxMatchLen <1OR maxMatchLen > CHAR_LENGTH(subject), CHAR_LENGTH(subject), maxMatchLen);-- Set the pattern to use to match an entire string rather than part of a stringSET usePattern = IF (LEFT(pattern, 1) ='^', pattern, CONCAT('^', pattern));SET usePattern = IF (RIGHT(pattern, 1) ='$', usePattern, CONCAT(usePattern, '$'));-- Set start position to 1 if pattern starts with ^ or doesn't end with $. IF LEFT(pattern, 1) ='^'OR RIGHT(pattern, 1) <>'$' THENSET startPos =1, startInc =1;-- Otherwise (i.e. pattern ends with $ but doesn't start with ^): Set start pos-- to the min or max match length from the end (depending on "greedy" flag). ELSEIF greedy THENSET startPos = CHAR_LENGTH(subject) - maxMatchLen +1, startInc =1; ELSESET startPos = CHAR_LENGTH(subject) - minMatchLen +1, startInc =-1; END IF; WHILE startPos >=1AND startPos <= CHAR_LENGTH(subject)AND startPos + minMatchLen -1<= CHAR_LENGTH(subject)AND !(LEFT(pattern, 1) ='^'AND startPos <>1)AND !(RIGHT(pattern, 1) ='$'AND startPos + maxMatchLen -1< CHAR_LENGTH(subject)) DO-- Set start length to maximum if matching greedily or pattern ends with $.-- Otherwise set starting length to the minimum match length. IF greedy OR RIGHT(pattern, 1) ='$' THENSET len = LEAST(CHAR_LENGTH(subject) - startPos +1, maxMatchLen), lenInc =-1; ELSESET len = minMatchLen, lenInc =1; END IF;SET prevStartPos = startPos; lenLoop: WHILE len >=1AND len <= maxMatchLenAND startPos + len -1<= CHAR_LENGTH(subject)AND !(RIGHT(pattern, 1) ='$'AND startPos + len -1<> CHAR_LENGTH(subject)) DOSET subStr =SUBSTRING(subject, startPos, len); IF subStr REGEXP usePattern THENSET result = IF(startInc =1, CONCAT(result, replacement), CONCAT(replacement, result));SET startPos = startPos + startInc * len; LEAVE lenLoop; END IF;SET len = len + lenInc; END WHILE; IF (startPos = prevStartPos) THENSET result = IF(startInc =1, CONCAT(result, SUBSTRING(subject, startPos, 1)), CONCAT(SUBSTRING(subject, startPos, 1), result));SET startPos = startPos + startInc; END IF; END WHILE; IF startInc =1AND startPos <= CHAR_LENGTH(subject) THENSET result = CONCAT(result, RIGHT(subject, CHAR_LENGTH(subject) +1- startPos)); ELSEIF startInc =-1AND startPos >=1 THENSET result = CONCAT(LEFT(subject, startPos), result); END IF; ELSESET result = subject; END IF; RETURN result;END//DELIMITER ;
Sours: https://gist.github.com/bludnic/cc57aa19091a5da2b1dda99341de6700
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REGEXP_REPLACE

Syntax

REGEXP_REPLACE(subject, pattern, replace)

Description

returns the string with all occurrences of the regular expression replaced by the string . If no occurrences are found, then is returned as is.

The replace string can have backreferences to the subexpressions in the form \N, where N is a number from 1 to 9.

The function follows the case sensitivity rules of the effective collation. Matching is performed case insensitively for case insensitive collations, and case sensitively for case sensitive collations and for binary data.

The collation case sensitivity can be overwritten using the (?i) and (?-i) PCRE flags.

MariaDB 10.0.5 switched to the PCRE regular expression library for enhanced regular expression performance, and was introduced as part of this enhancement.

MariaDB 10.0.11 introduced the default_regex_flags variable to address the remaining compatibilities between PCRE and the old regex library.

Examples

SELECT REGEXP_REPLACE('ab12cd','[0-9]','') AS remove_digits; -> abcd SELECT REGEXP_REPLACE('<html><head><title>title</title><body>body</body></htm>', '<.+?>',' ') AS strip_html; -> title body

Backreferences to the subexpressions in the form , where N is a number from 1 to 9:

SELECT REGEXP_REPLACE('James Bond','^(.*) (.*)$','\\2, \\1') AS reorder_name; -> Bond, James

Case insensitive and case sensitive matches:

SELECT REGEXP_REPLACE('ABC','b','-') AS case_insensitive; -> A-C SELECT REGEXP_REPLACE('ABC' COLLATE utf8_bin,'b','-') AS case_sensitive; -> ABC SELECT REGEXP_REPLACE(BINARY 'ABC','b','-') AS binary_data; -> ABC

Overwriting the collation case sensitivity using the (?i) and (?-i) PCRE flags.

SELECT REGEXP_REPLACE('ABC','(?-i)b','-') AS force_case_sensitive; -> ABC SELECT REGEXP_REPLACE(BINARY 'ABC','(?i)b','-') AS force_case_insensitive; -> A-C

Comments

Sours: https://mariadb.com/kb/en/regexp_replace/
MySQL Database Tutorial - 15 - Regular Expressions
  • ,

    This is the same as .

  • ,

    Returns 1 if the string matches the regular expression specified by the pattern , 0 otherwise. If or is , the return value is .

    and are synonyms for .

    For additional information about how matching occurs, see the description for .

  • Returns the starting index of the substring of the string that matches the regular expression specified by the pattern , 0 if there is no match. If or is , the return value is . Character indexes begin at 1.

    takes these optional arguments:

    • : The position in at which to start the search. If omitted, the default is 1.

    • : Which occurrence of a match to search for. If omitted, the default is 1.

    • : Which type of position to return. If this value is 0, returns the position of the matched substring's first character. If this value is 1, returns the position following the matched substring. If omitted, the default is 0.

    • : A string that specifies how to perform matching. The meaning is as described for .

    For additional information about how matching occurs, see the description for .

  • Returns 1 if the string matches the regular expression specified by the pattern , 0 otherwise. If or is , the return value is .

    The pattern can be an extended regular expression, the syntax for which is discussed in Regular Expression Syntax. The pattern need not be a literal string. For example, it can be specified as a string expression or table column.

    The optional argument is a string that may contain any or all the following characters specifying how to perform matching:

    • : Case-sensitive matching.

    • : Case-insensitive matching.

    • : Multiple-line mode. Recognize line terminators within the string. The default behavior is to match line terminators only at the start and end of the string expression.

    • : The character matches line terminators. The default is for matching to stop at the end of a line.

    • : Unix-only line endings. Only the newline character is recognized as a line ending by the , , and match operators.

    If characters specifying contradictory options are specified within , the rightmost one takes precedence.

    By default, regular expression operations use the character set and collation of the and arguments when deciding the type of a character and performing the comparison. If the arguments have different character sets or collations, coercibility rules apply as described in Section 10.8.4, “Collation Coercibility in Expressions”. Arguments may be specified with explicit collation indicators to change comparison behavior.

    may be specified with the or characters to override the default case sensitivity. Exception: If either argument is a binary string, the arguments are handled in case-sensitive fashion as binary strings, even if contains the character.

    Note

    MySQL uses C escape syntax in strings (for example, to represent the newline character). If you want your or argument to contain a literal , you must double it. (Unless the SQL mode is enabled, in which case no escape character is used.)

  • Replaces occurrences in the string that match the regular expression specified by the pattern with the replacement string , and returns the resulting string. If , , or is , the return value is .

    takes these optional arguments:

    • : The position in at which to start the search. If omitted, the default is 1.

    • : Which occurrence of a match to replace. If omitted, the default is 0 (which means “replace all occurrences”).

    • : A string that specifies how to perform matching. The meaning is as described for .

    Prior to MySQL 8.0.17, the result returned by this function used the character set; in MySQL 8.0.17 and later, the character set and collation of the expression searched for matches is used. (Bug #94203, Bug #29308212)

    For additional information about how matching occurs, see the description for .

  • Returns the substring of the string that matches the regular expression specified by the pattern , if there is no match. If or is , the return value is .

    takes these optional arguments:

    • : The position in at which to start the search. If omitted, the default is 1.

    • : Which occurrence of a match to search for. If omitted, the default is 1.

    • : A string that specifies how to perform matching. The meaning is as described for .

    Prior to MySQL 8.0.17, the result returned by this function used the character set; in MySQL 8.0.17 and later, the character set and collation of the expression searched for matches is used. (Bug #94203, Bug #29308212)

    For additional information about how matching occurs, see the description for .

  • Sours: https://dev.mysql.com/doc/refman/8.0/en/regexp.html

    Mysql regexp_replace

    MySQL REGEXP_REPLACE()

    MySQL REGEXP_REPLACE()

    Definition of MySQL REGEXP_REPLACE()

    REGEXP_REPLACE() operator is used in the SELECT query, to replace the matched sub-string. This operator searches for the regular expression identifies it, replaces the pattern with the sub-string provided explicitly in the query, and returns the output with the updated sub-string. This function is rarely used but has a good impact when used. Sub-string can be replaced as a whole, at a specified position, or in an array. In this article, we will discuss MySQL REGEXP_REPLACE() in detail and also, we can discuss in detail about the syntax and the use in the following portions.

    Syntax

    Simplest syntax for REGEXP_REPLACE() function is as follows:

    Here, exp is the string to be searched upon, pat is the regular expression searched for, and repl is the sub-string which will be replaced.

    When used in a SELECT query, the query can be as below:

    A further detailed syntax for REGEXP_REPLACE() is as follows:

    In this, the pos, pat, repl are optional arguments. Pos stands for the position in the string where the search is to be performed. This can be omitted in the query, which will lead the search to start at the first character. Occurrence specifies which occurrence of the expression is to be replaced. This argument can also be omitted and instead, all occurrences will be replaced. Match_type specifies how the matching is to be performed.

    We can now take a detailed look at the practical examples of REGEXP_REPLACE() operator.

    How REGEXP_REPLACE() works in MySQL?

    Consider the string as below:

    MySQL REGEXP_REPLACE() 1-1

    The string is having data as ‘I am robot. I can read, write, and process.’. This is our test string, where we will work on the different REPLACE() operations.

    Query 1

    Output:

    MySQL REGEXP_REPLACE() 2

    The query is expected to search the string to find the sub-string ‘robot’, replace it by sub-string ‘Human’ and then return the updated string. The regular expression is to be searched within the ‘string’. The expis the ‘string’, the pattern to be searched, pat, is the sub-string ‘robot’, and the replacing sub-string (rep) will be ‘Human;.

    In the output, we can see, the sub-string ‘robot’ is replaced as ‘Human; and updated string that is returned by the SELECT query is ‘I am Human. I can read, write, and process.’

    Query 2

    Let’s now write the query to replace multiple occurrences of a sub-string with the same replacing expression.

    The expected output is to replace all upper case ‘I’ to lower case ‘i’ in the string. Though in our query, we have mentioned only once, upper case ‘I’ appears twice in the string.

    Output:

    MySQL REGEXP_REPLACE() 3

    We can see, in the output that both the upper case ‘I ‘are replaced with lower case ‘i’.

    Query 3

    The replacing function will return a null value if the sub-string (expression) is not present in the string. The query to validate that scenario will be as follows:

    Our string does not have the sub-string ‘also’. So the output should not be affected with the replacement clause, instead, it should be the same as the input.

    Output:

    MySQL REGEXP_REPLACE() 4

    We discussed the optional arguments of REPLACE() function. Let’s see how to use them in practical scenarios. Let’s consider the original string to be as below:

    Query 4

    We can see the use of position argument.

    Query is to return the string updated as from the second position of sub-string ‘Table’ replaced by ‘*****’.

    Output:

    MySQL REGEXP_REPLACE() 5

    We had sub-string ‘Table’ three times in the original string. The query returned the first sub-string of ‘Table’ as is and replaced the second and third sub-strings as ‘*****’.

    Query 5

    In the above query, all occurrences of the specified sub-strings, from a particular position, were replaced. Instead, let us see how we can replace only one occurrence of sub-string ‘Table’ from the original string.

    The query is expected to return the string with only the second occurrence of sub-string ‘Table’ replaced by ‘*****’. Here the sub-strings are to be counted from the first position.

    Output:

    Query 5

    We can see, among the three occurrences of ‘Table’ sub-string, only the second one (when counted from first one) is replaced.

    The same query can give a different output if we change the position of occurrence count.

    result 1

    The Output will be updating the second occurrence of ‘Table’ from the second position. Or change the occurrence count as below:

    The output will be updating the first occurrence of ‘Table’ from the first position.

    result 2

    Finally, let’s explore the match_type argument. There are several characters in this argument. They are

    •  ‘c’ – this will enable a case sensitive matching
    •  ‘i’ – this will enable a case insensitive matching
    • ‘m’ – this will identify where the line is terminated
    • ’n’ – this will identify the line terminators ‘.’.

    Query 6

    The pattern to be searched in this query is ‘table’, with all lower case characters. The query is expected to return three cases:

    1. The original string with three occurrences of the sub-string ‘table’.
    2. A case sensitive result where the second occurrence of sub-string ‘table’ to be replaced by ‘*****’. This will not replace the sub-string, because the original string has ‘Table’ sub-string with an upper case ‘T’.
    3. A case insensitive result where the second occurrence of sub-string ‘table’ to be replaced by ‘*****’. This portion of string will update the sub-string ‘table’ with ‘*****’.

    Output:

    result grid

    The output will have the case insensitive result field with ‘table’ replaced by ‘*****’.

    Conclusion – MySQL REGEXP_REPLACE()

    In this chapter, we have discussed different options of using REGEXP_REPLACE() function. The function, as discussed replaces the regular expression with the sub-string specified in the SELECT query.

    Recommended Articles

    This is a guide to MySQL REGEXP_REPLACE(). Here we discuss MySQL REGEXP_REPLACE() along with appropriate syntax and respective examples. You may also have a look at the following articles to learn more –

    1. MySQL Subquery
    2. ANY in MySQL
    3. MySQL Constraints
    4. ROLLUP in MySQL
    Sours: https://www.educba.com/mysql-regexp_replace/
    SQL Query - Replace special characters - Control Characters - REPLACE function

    MariaDB: REGEXP_REPLACE Function

    totn MariaDB Functions

    This MariaDB tutorial explains how to use the MariaDB REGEXP_REPLACE function with syntax and examples.

    Description

    The MariaDB REGEXP_REPLACE function is an extension of the REPLACE function. This function, introduced in MariaDB 10.0.5, will allow you to replace all occurrences of a substring in a string using regular expression pattern matching.

    Syntax

    The syntax for the REGEXP_REPLACE function in MariaDB is:

    REGEXP_REPLACE( string, pattern, replacement )

    Parameters or Arguments

    string
    The string to search.
    pattern

    The regular expression matching information. It can be a combination of the following:

    ValueDescription
    ^Matches the beginning of a string. If used with a match_parameter of 'm', it matches the start of a line anywhere within expression.
    $Matches the end of a string. If used with a match_parameter of 'm', it matches the end of a line anywhere within expression.
    *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.
    [ ]Used to specify a matching list where you are trying to match any one of the characters in the list.
    [^ ]Used to specify a nonmatching list where you are trying to match any character except for the ones in the list.
    ( )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.
    [..]Matches one collation element that can be more than one character.
    [::]Matches character classes.
    [==]Matches equivalence classes.
    \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.
    replacement
    The replacement substring. All occurrences of pattern found within string are replaced with replacement.

    Note

    • If the REGEXP_REPLACE function does not find any occurrence of pattern, it will return the original string without any changes.
    • This page applies to MariaDB 10.0.5 and higher, which uses the PCRE regex library.
    • See also the REPLACE function.

    Applies To

    The REGEXP_REPLACE function can be used in the following versions of MariaDB:

    Example - Match on more than one alternative

    Let's start by looking how to use the pattern with the REGEXP_REPLACE function in MariaDB.

    For example:

    SELECT REGEXP_REPLACE ('TechOnTheNet','a|e|i', '8'); Result: 'T8ch8nTh8N8t'

    These REGEXP_REPLACE examples will replace all occurrences of the letters "a", "e", "i" or "o" in the string "TechOnTheNet" with "8". The REGEXP_REPLACE function performs a case-insensitive search so it doesn't matter whether "a", "e", "i" or "o" values are uppercase or lowercase.

    Case Sensitive Search

    If we wanted to perform a case-sensitive search, we need to modify our REGEXP_REPLACE function to use a binary string. This can be done using the pattern.

    SELECT REGEXP_REPLACE ('TechOnTheNet', '(?-i)a|(?-i)e|(?-i)i|(?-i)o', '8'); Result: 'T8chOnTh8N8t'

    In this example, we have used the we used the pattern to force the REGEXP_REPLACE function to perform case-sensitive pattern matching. So now the "O" character that is uppercase in "TechOnTheNet" is not replace with "8".

    Table Column Search

    Now let's show how to use the REGEXP_REPLACE function with a table column:

    So let's say we have a contact table with the following data:

    contact_idlast_name
    1000Anderson
    2000Smith
    3000Johnson

    Now, let's run the following query:

    SELECT contact_id, last_name, REGEXP_REPLACE (last_name, 'a|e|i|o|u', "z") AS Result FROM contacts;

    These are the results that would be returned by the query:

    contact_idlast_nameResult
    1000Andersonzndzrszn
    2000SmithSmzth
    3000JohnsonJzhnszn

    Example - Match on Words

    Next, let's look at how to use the REGEXP_REPLACE function to replace the first word in a string.

    For example:

    SELECT REGEXP_REPLACE ('TechOnTheNet is a great resource', '(\\S*)', 'CheckYourMath'); Result: 'CheckYourMath is a great resource'

    This example will return 'CheckYourMath is a great resource' because it will replace all non-whitespace characters as specified by and stop when it hits the first whitespace character (ie: space character). That will result in the word 'TechOnTheNet' being replaced with 'CheckYourMath'.

    Example - Match on Digit Characters

    Now, let's look next at how we would use the REGEXP_REPLACE function to match on a digit character pattern.

    For example:

    SELECT REGEXP_REPLACE ('7, 8, and 15 are numbers in this example', '\\d', 'abc'); Result: 'abc, abc, and abcabc are numbers in this example'

    This example will replace numeric digits in the string with "abc" as specified by . In this case, it will match on the numbers 7, 8, and 15.

    We could change our pattern to replace only two-digit numbers.

    For example:

    SELECT REGEXP_REPLACE ('7, 8, and 15 are numbers in this example', '(\\d)(\\d)', 'abc'); Result: '7, 8, and abc are numbers in this example'

    This example will replace all two-digit numbers with "abc" as specified by . In this case, it will skip over the 7 and 8 numeric values and only replace the number 15.

    Now, let's look how we would use the REGEXP_REPLACE function with a table column and search for a two digit number.

    For example:

    SELECT REGEXP_REPLACE (address, '\\d', '') FROM contacts;

    In this example, we are going to remove all numbers from the address field in the contacts table. This is done by searching for all numbers using and replacing with "".

    Sours: https://www.techonthenet.com/mariadb/functions/regexp_replace.php

    You will also like:

    How to do a regular expression replace in MySQL?

    UPDATE 2: A useful set of regex functions including REGEXP_REPLACE have now been provided in MySQL 8.0. This renders reading on unnecessary unless you're constrained to using an earlier version.


    UPDATE 1: Have now made this into a blog post: http://stevettt.blogspot.co.uk/2018/02/a-mysql-regular-expression-replace.html


    The following expands upon the function provided by Rasika Godawatte but trawls through all necessary substrings rather than just testing single characters:

    Demo

    Rextester Demo

    Limitations

    1. This method is of course going to take a while when the subject string is large. Update: Have now added minimum and maximum match length parameters for improved efficiency when these are known (zero = unknown/unlimited).
    2. It won't allow substitution of backreferences (e.g. , etc.) to replace capturing groups. If this functionality is needed, please see this answer which attempts to provide a workaround by updating the function to allow a secondary find and replace within each found match (at the expense of increased complexity).
    3. If and/or is used in the pattern, they must be at the very start and very end respectively - e.g. patterns such as are not supported.
    4. There is a "greedy" flag to specify whether the overall matching should be greedy or non-greedy. Combining greedy and lazy matching within a single regular expression (e.g. ) is not supported.

    Usage Examples

    The function has been used to answer the following StackOverflow questions:

    Sours: https://stackoverflow.com/questions/986826/how-to-do-a-regular-expression-replace-in-mysql


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