: This is SQL shorthand to comment out the rest of the legitimate code, ensuring the injected command runs cleanly. The "DJGP" Element

: They use "NULL" to figure out exactly how many columns your database table has without triggering a data-type error.

In the world of cybersecurity, "DJGP" or similar tags are often used as unique identifiers by automated scanners or bug hunters. When a researcher (or a bot) sends this payload, they aren't looking to steal data immediately—they are looking for a . If "DJGP" shows up in the webpage's output, they know the site is vulnerable and can be exploited. How to Stay Safe

If you expect a zip code, don't accept a string that starts with UNION .