{keyword}) Union All Select Null,null,null,null,null-- Zkhd 〈Must Try〉

: This is likely a random string or a "signature" used by a vulnerability scanner (like Burp Suite or sqlmap) to track if the payload was successfully reflected in the application's response.

: The number of NULL values (5 in this case) does not match the number of columns in the original table. {KEYWORD}) UNION ALL SELECT NULL,NULL,NULL,NULL,NULL-- ZkhD

For more in-depth technical guides, you can visit the Web Security Academy or community forums like Medium . : This is likely a random string or