Invoking a PHP script from a MySQL trigger

It is possible to invoke a PHP script from a MySQL trigger by using the system() function in the trigger's body. The system() function allows you to execute a system command, such as running a script. For example, you can create a trigger that runs a PHP script every time a specific table is updated by including the following line of code in the trigger's body:

system("php /path/to/script.php");

It's worth to mention that, for security reasons, it's not recommended to use system commands with variables that depend on user input, as it could lead to potential security issues such as SQL injection.

Also, bear in mind that the system command is executed by the MySQL server, so you must make sure that the PHP interpreter is installed and available on the server, and that the user running the MySQL server has the appropriate permissions to execute the script.