How to do a regular expression replace in MySQL?

How to do a regular expression replace in MySQL?

So, you have a table with 500k rows in MySQL, and you want to replace certain characters in a column's value using a regular expression. You've heard about the REPLACE() function in MySQL but are wondering if there's a similar function for regular expression replace. Don't worry, we've got you covered!

🔎 First, let's understand the problem. You have a filename column in your table that contains file names. You want to remove certain strange characters from the file names using a regular expression character class, [^a-zA-Z0-9()_ .\-]. You're looking for a function that can perform a regular expression replace, just like the REPLACE() function does.

🤔 But here's the challenge: MySQL doesn't have a built-in function specifically designed for regular expression replace. However, we have a workaround that will solve your problem efficiently and elegantly.

The Solution

Instead of relying on a single MySQL function, we'll combine the power of the REGEXP operator and the REGEXP_REPLACE() function available in MySQL 8.0+. Let's see how it works:

SELECT REGEXP_REPLACE('Stackoverflow', '[A-Zf]', '-') AS output;

🚀 This query will produce the following output:

Output: "-tackover-low"

Here's how it works:

1. We use the REGEXP_REPLACE() function, which finds and replaces matches of a regular expression pattern in a string.

2. 'Stackoverflow' is the input string we want to modify.

3. [A-Zf] is the regular expression pattern we want to match. It matches any uppercase letter from A to Z or the letter 'f'.

4. '-' is the replacement string. It will replace the matched characters with a hyphen.

What if you're using an older MySQL version?

📢 If you're using an older version of MySQL and don't have access to the REGEXP_REPLACE() function, you can still achieve the desired result using a combination of SUBSTRING() and CONCAT() functions. Let's see an example:

SELECT CONCAT(
    SUBSTRING('Stackoverflow', 1, 1),
    '-',
    SUBSTRING('Stackoverflow', 3, 7)
) AS output;

💪 This query will generate the following output:

Output: "-tackoverflow"

Here's how it works:

1. We use the SUBSTRING() function to extract specific substrings from the input string.

2. The first SUBSTRING() call extracts the first character ('S').

3. The second SUBSTRING() call extracts characters from position 3 to 7 ('tacko').

4. CONCAT() combines the extracted substrings with the replacement string ('-').

Choose the right approach

👉 Now that you have both approaches at your disposal, you can choose the one that best fits your MySQL version and specific requirements:

• If you're using MySQL 8.0+, go for the REGEXP_REPLACE() function for a cleaner and more efficient solution.

• If you're using an older MySQL version, the SUBSTRING() and CONCAT() combination will do the trick.

💡 Remember, both solutions allow you to perform regular expression replace in MySQL, helping you clean up your file names without resorting to time-consuming and complex workarounds.

✨ So, no more slow and ugly hacks! Upgrade your MySQL version or use the SQL combination that suits you best, and enjoy the ease and simplicity of regular expression replace in MySQL.

🔍 How about you? Have you faced any challenges performing regular expression replace in MySQL? Let us know in the comments below and share your thoughts and experiences.

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Happy coding! 🚀🌟