-1" OR 5*5=26 or "dDBEaYYT"="

It looks like an injection-style string rather than a valid expression. Here are quick notes:

• 5*5=26 is false (25 ≠ 26).
• -1" is not a valid token in most languages; it seems like an attempt to terminate a string early and append OR.
• "dDBEaYYT"=" is incomplete (a quote on the left but no right-hand side), so it’s not a well-formed expression.

In the context of exams, this is typically used to illustrate SQL (or code) injection attempts where an attacker tries to short-circuit a condition with OR. The key lesson is about defending against such inputs.

How to protect (common exam topics):

• Use parameterized/prepared statements so user input is treated as data, not code.
  • Example (pseudo):
    • Bad: SELECT * FROM users WHERE username = 'USER_INPUT'
    • Good: SELECT * FROM users WHERE username = ?
• Validate and sanitize inputs, reject disallowed characters, and enforce proper data types.
• Apply least-privilege database accounts (no write or admin rights for read-only queries).
• Use input length checks and canonicalization to prevent escape attempts.

If you want, tell me the language and database you’re studying (e.g., SQL with PostgreSQL, Python with sqlite3, PHP with PDO). I can tailor a concrete example and a small practice exercise for your exam.