-1' OR 3*2<5 or 'NyqYC96j'='

That string looks like a fragment of an SQL injection payload. It appears to try to terminate a string in a query and inject an OR condition to alter the WHERE clause. The part 3*2<5 evaluates to false (since 6 < 5 is false). The overall effect (and whether it works) depends on the surrounding query and whether the input is properly handled.

Key points:

• It’s a boolean-based injection attempt: injecting OR conditions to change the logic of the query.
• If the application uses string concatenation to build SQL with user input, this can lead to bypasses or errors.
• As written, the payload is incomplete and would likely cause a syntax error in a real query unless the rest of the string is crafted to comment out or close the syntax.

Defensive measures (for exam prep and real systems):

• Use prepared statements / parameterized queries everywhere. Do not concatenate user input into SQL.
  • Examples (conceptual):
    • Python: cur.execute("SELECT * FROM users WHERE username = %s AND password = %s", (username, password))
    • Java: PreparedStatement ps = conn.prepareStatement("SELECT * FROM users WHERE username = ? AND password = ?"); setString(1, username); setString(2, password);
    • Node.js (mysql2): connection.execute("SELECT * FROM users WHERE username = ? AND password = ?", [username, password])
• Validate and whitelist input where possible (e.g., length checks, allowed character sets).
• Use least-privilege database accounts and avoid running application queries with admin rights.
• Disable verbose database error messages that reveal query structure.
• Consider using ORM or query builders that handle parameterization automatically.

If you want, tell me the language/framework you’re studying, and I can tailor safe, exam-style examples and explain typical vulnerabilities and mitigations for that setup.