{keyword}) Union All Select Null,null,null,null,null-- Zkhd | TRUSTED ★ |

An attacker (or security researcher) would send this payload to an application to see if it returns an error or a successful response.

: The original table has exactly 5 columns. This confirms a vulnerability and allows the attacker to move to the next step: identifying which columns can display sensitive data. {KEYWORD}) UNION ALL SELECT NULL,NULL,NULL,NULL,NULL-- ZkhD

: The number of NULL values (5 in this case) does not match the number of columns in the original table. An attacker (or security researcher) would send this

: The attacker uses a specific number of NULL values to match the number of columns in the original query's SELECT statement. NULL is used because it is compatible with almost any data type (strings, integers, dates), maximizing the chance that the injected query will succeed. {KEYWORD}) UNION ALL SELECT NULL,NULL,NULL,NULL,NULL-- ZkhD