Can MySQL replace multiple characters?

sql

regexp

mysql-features

string-manipulation

byAnton Shumikhin·Sep 2, 2024

Implement multiple character substitutions in MySQL with chained REPLACE() functions:

SELECT REPLACE(REPLACE(REPLACE(column, 'a', '!'), 'b', '?'), 'c', '#') AS updated
FROM your_table;

Inside each REPLACE(), a different character swap occurs: 'a' -> '!', 'b' -> '?'**, 'c' -> '#'. Nest to run sequential character replacements in a single query.

Leveraging REGEXP_REPLACE in MySQL 8.0+

For advanced character substitutions, use REGEXP_REPLACE:

-- Let's play 'X-Men', but with regex
SELECT REGEXP_REPLACE(column, '[abc]', 'X') AS updated
FROM your_table;

Here, each character in the [abc] set is replaced with 'X'. This approach is efficient for handling complex pattern replacements.

Crafting custom functions: The freedom to customize

Create custom functions when built-in utilities fall short:

-- Rolling out my bespoke function, dressed to kill
DELIMITER //
CREATE FUNCTION custom_replace(str TEXT) RETURNS TEXT
BEGIN
    RETURN REPLACE(REPLACE(REPLACE(str, 'a', '!'), 'b', '?'), 'c', '#');
END; //
DELIMITER ;

Invoke it like SELECT custom_replace(column) FROM your_table;. This approach encapsulates the replacement operations, reducing duplication.

Dealing with nulls: The IFNULL lifebuoy

Preserve data integrity by handling null values elegantly:

-- I don't always replace characters, but when I do, I handle nulls
SELECT 
    REPLACE(IFNULL(column, ''), 'a', '!') AS safeguarded_updated
FROM your_table;

The IFNULL function ensures that a null field won't halt the replacement process.

Going beyond simple replacements

Simultaneous character replacements may sometimes be more intricate, necessitating a sophisticated understanding of patterns and clever utilization of MySQL features:

Recognize patterns in data and use REGEXP_REPLACE for accurate data targeting.
Bundle complex string manipulations into a custom function for convenience.
Nested REPLACE() can cause unexpected character replacements due to sequence.
Amplify your MySQL functionality via the lib_mysqludf_preg library for advanced regex features in older versions.

Navigating pitfalls and troubleshooting

Nested REPLACE() operations can inadvertently alter previously replaced characters. To avoid this, carefully plan your sequence:

-- Watch out for the double agents: the problem sequence
REPLACE(REPLACE(column, '1', '2'), '2', '3')

-- The Save-the-day sequence
REPLACE(REPLACE(column, '2', '3'), '1', '2')