{keyword}' Union All Select Null-- Xiuj Apr 2026

The query ' UNION ALL SELECT NULL-- is a classic payload used in attacks to determine the structure of a database query. It is used when an application is vulnerable to SQL injection and returns query results directly in its HTTP responses.

Comments out the rest of the original SQL query, preventing syntax errors caused by the remaining code. Purpose and Techniques SQL injection UNION attacks | Web Security Academy {KEYWORD}' UNION ALL SELECT NULL-- xIuj

Combines the results of the original, intended query with the results of a new, malicious query. The query ' UNION ALL SELECT NULL-- is

Selects NULL values to match the number of columns in the original query. NULL is used because it is compatible with almost all data types. Purpose and Techniques SQL injection UNION attacks |

Closes the original input string, allowing the attacker to break out of the intended query structure.