: A function used to query XML data. If given an invalid path (which this payload provides), it throws a database error.
The string you've provided is an example of a used in automated vulnerability scanning or attacks. It is not a legitimate "proper feature" of a software application; rather, it is designed to exploit security flaws in a database's error-handling mechanism. Breakdown of the Payload : A function used to query XML data
: Attempts to close a single-quoted string literal in the original SQL query. : A function used to query XML data