Union All Select Null,null,null,null-- Uizf - {keyword}

: This represents the original search term or input field. The attacker appends the malicious code to this keyword.

: The attacker is attempting to determine the number of columns returned by the original database query. By adding NULL values until the page loads without an error, they can identify the table's structure. {KEYWORD} UNION ALL SELECT NULL,NULL,NULL,NULL-- Uizf

: Once the column count is known, they replace the NULL values with actual commands (e.g., version() , user() , or table_name ) to steal sensitive information. : This represents the original search term or input field

If you found this in a "complete report" (such as a security scan or a web server log), it indicates that an automated tool or a manual actor has the system. By adding NULL values until the page loads

: Confirm that the application is vulnerable to SQL injection.