Not an SQL injection, but I opened Google in a private browsing window, searched for “php mysql tutorial”, and it brought me to the W3Schools tutorial, which has multiple other vulnerabilities relating to how PHP just dumps its output into HTML unescaped without a second thought. At a glance, I see obvious XSS and open redirect vulnerabilities.
It’s the top hit for “PHP MySQL tutorial”. This is what PHP newbies are learning from.
The same tutorial with Django wouldn’t have the same problem because Django auto-escapes strings you dump into HTML. These vulnerabilities only exist in this tutorial because PHP treats its output as HTML by default not text, so you need to put in extra effort to be secure.
https://www.w3schools.com/php/php_mysql_select.asp