Null,null,null,null,null,null,null,null,null,null-- Zvuz | {keyword} Union All Select

: These tools can automatically detect and block common SQLi patterns like the one you provided.

: Once the column count is known, the attacker replaces the NULL s with commands to extract sensitive data, such as usernames, passwords, or credit card numbers. Prevention and Best Practices : These tools can automatically detect and block

: This is a SQL comment symbol. It tells the database to ignore everything that follows it, effectively neutralizing the rest of the original, legitimate code. such as usernames