• Dec 22, 2023 modified: Jul, 29 2026

MySQL Regexp Administrative Helpers

The MySQL database provides a powerful way to perform complex text-based searches through the regular expressions function REGEXP.

Many websites are operating a MySQL database. Often we create web forms to capture contact information.

Hence some very powerful features are available to help organise that data when we combine Regexp with MySQL.

MySQL Regexp Examples

Task: Find all Customers with Phone Numbers that contain a + or - character in the Home_Ph field.

WHERE Home_Ph REGEXP '[+-]'

If we only wanted to find the numbers with a + symbol-:

WHERE Home_Ph REGEXP '[+]'

Task: If we wanted to find the emails that contain hotmail-:

WHERE Email REGEXP 'hotmail'

Task: If we wanted to find malformed emails-:

WHERE Email NOT REGEXP '^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+.[A-Za-z]{2,}$'

Task: If we wanted to find the post codes that contain 4 digits-:

WHERE Post_Code REGEXP '^[[:digit:]]{4}$';

OR

WHERE Post_Code REGEXP '^[0-9]{4}$';

Source: How to Use MySQL Regular Expressions

Task: Remove HTML tags from text efficiently

In our custom systems we may add a site search to a site that has a large number of news articles. There is no point adding a site search if there are only a few articles. Manually going through every table and removing the HTML tags is tedius. This can be done programatically in Java for every updated article. But how do we efficiently remove tags from articles that are not updated? It can be done with the following in MySQL 8-:

You could leave the tags in and wait until every article is updated. However the efficiency of the query would be affected by the letters in the tags.

Using the Powerful Features of your Database

MySQL is very good at handling many clients connecting and disconnecting to the database at a high frequency, up to 80 thousand connect and disconnects per second according to https://dev.mysql.com/blog-archive/mysql-connection-handling-and-scaling/.

That means your website database is incredibly evolved and efficient.

We wanted to build a system that better utilised the powerful features of our back-end systems. Why not make the website that collects the data also a powerful CRM tool?

We have the ability to monitor customer behaviour. Nothing sinister or breaches of privacy, just being able to detect which opt in customers are more interested in certain products or services.

Email Marketing from the same system, opens up even more power. Any system that requires duplication of data can be wasteful and inefficient.