: This is the core of the attack. It tells the database to combine the results of the legitimate query with the results of a new, malicious one.

Are you seeing this in your , or are you testing the security of your own code ?

: Use parameterized queries so that user input is never executed as code.

: This is likely a "canary" or a unique identifier used by automated security scanners to confirm if the injection was successful. What should you do?

: The attacker uses NULL values to figure out how many columns are in the original database table. If the number of NULL s doesn't match the number of columns in the original query, the database will return an error.

If you found this in your website's logs, it means someone (or an automated bot) was . It is a common sign of a "SQLi" attack. To protect your application, you should:

: A WAF can often block these types of patterned attacks automatically.

The string you provided is a . Specifically, it is designed to exploit a vulnerability in a database-driven application to extract unauthorized data.