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