How Can I Use REGEXP_REPLACE to Modify Data in MySQL Using Regular Expressions?

Regular Expression Replace in MySQL

When dealing with large datasets, it often becomes necessary to cleanse or modify data based on specific patterns. In MySQL, the task of replacing characters or substrings within a column using regular expressions can be achieved using the newer REGEXP_REPLACE function, available in MariaDB and MySQL 8.0.

REGEXP_REPLACE Syntax

The syntax of the REGEXP_REPLACE function is:

REGEXP_REPLACE(col, regexp, replace)

where:

• col is the column you wish to modify
• regexp is the regular expression pattern you want to match
• replace is the string you want to replace the matched pattern with

Example Usage

Suppose you have a table with a column named filename that contains file names, and you want to remove any special characters (e.g., digits, punctuation) except for the following: a-z, A-Z, (,), _, ., and -. You can use the REGEXP_REPLACE function as follows:

SELECT REGEXP_REPLACE(filename, '[^a-zA-Z0-9()_ .\-]', '')

This will return a new column with the modified file names.

Grouping

The REGEXP_REPLACE function also supports grouping, allowing you to perform more complex replacements. For instance, you can use grouping to extract portions of the matched pattern and use them in the replacement string.

SELECT REGEXP_REPLACE("stackoverflow", "(stack)(over)(flow)", '\2 - \1 - \3')

This will return the following:

over - stack - flow

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