: This is the most effective defense.
: In MySQL, this character marks the rest of the query as a comment, effectively "breaking" any remaining original code that might cause the attack to fail. Why are you seeing this?
The string you've provided, "-1697 UNION ALL SELECT 34#" , is a classic example of a payload. This specific syntax is often used by security researchers or attackers to test if a database-driven website is vulnerable to unauthorized data access. What this string does:
: These can block common "UNION ALL" patterns before they ever reach your database.
: Ensure that if a field expects a number, it only receives a number.
To prevent these types of attacks, developers should never insert user input directly into SQL queries. Instead, you should use:
: This is the "injection" part. It tells the database to append a second result set (containing the number 34 ) to the first (empty) result set. If the page then displays "34", the attacker knows the site is vulnerable and that they can use this spot to extract sensitive data like usernames or passwords.
: This is a dummy value. By using a negative or non-existent ID, an attacker forces the original database query to return no results.