If the page returns an error (like "The used SELECT statements have a different number of columns"), the attacker will try again with five or seven NULL values until the error disappears. 4. -- (The Comment) In SQL, double-dashes signify the start of a comment.
: For a UNION to work, the second query must have the exact same number of columns as the first query. 3. SELECT NULL,NULL,NULL,NULL,NULL,NULL If the page returns an error (like "The
Developers should use Parameterized Queries (Prepared Statements), which treat user input as literal data rather than executable code. If the page returns an error (like "The
: NULL is used because it is compatible with almost any data type (integers, strings, dates, etc.). If the page returns an error (like "The