Null,null,null,null,null,null,null,null-- Mxyc | {keyword}') Union All Select

: This is the SQL comment symbol. It tells the database to ignore everything else in the original code, effectively "turning off" the security checks or logic that were supposed to happen next. The Goal: Data Exfiltration

It looks like you've included a in your request. In the world of cybersecurity, that specific snippet is a classic example of an "Union-based" attack. : This is the SQL comment symbol

Modern web development has largely moved past this threat using a technique called (or Parameterized Queries). Instead of letting user input mix directly with the code, the database is told: "Treat this input strictly as text, no matter what symbols are inside it." : This is the SQL comment symbol