: This operator combines the results of two different SELECT statements into a single result set.

If you were looking to write a blog post about this topic, here is a quick breakdown of what it means and why it matters: What is SQL Injection (SQLi)?

: In MySQL, this is a comment symbol. It tells the database to ignore the rest of the legitimate code, preventing syntax errors that would break the attack. Why You Should Care

: This is a dummy value. By using a negative or non-existent ID, the attacker ensures the first part of the query returns no results, making room for the injected data to show up.

Access private user info or credit card numbers. Bypass Login: Log in as an admin without a password. Wreak Havoc: Delete or modify entire databases. How to Stay Safe

: The attacker is trying to match the number of columns in the original query. If the page loads "34," they know the table has two columns and they can start pulling real data (like usernames or passwords) in those slots.