{keyword}) Union All Select Null,null,null,null,null,null# -

: This part attempts to "break out" of the existing SQL command. The closing parenthesis ) is used to close a function or a nested query that the developer originally intended.

: This is a common reconnaissance technique. An attacker uses NULL values to determine the exact number of columns returned by the original query. If the number of NULL s doesn't match the original column count, the database will usually throw an error. By adding or removing NULL s, an attacker can find the correct structure. {KEYWORD}) UNION ALL SELECT NULL,NULL,NULL,NULL,NULL,NULL#

: In MySQL, the hash symbol marks the rest of the line as a comment . This effectively deletes any remaining parts of the original developer's code (like a trailing WHERE clause or a closing quote) that would otherwise cause a syntax error. Why This Matters : This part attempts to "break out" of

: This treats user input as data, not as executable code. An attacker uses NULL values to determine the