Junior From PDF SQL SQL & Databases

What is SQL injection and how do you prevent it?

Q: What is SQL injection and how do you prevent it?

Short answer: SQL Injection is a type of attack where an attacker inserts or manipulates malicious SQL code into a query, which can compromise the database. Explain a bit more It usually happens when user input is improperly sanitized or validated. Prevention techniques: Use Prepared Statements/Parameterized Queries: This ensures that user input is treated as data, not executable code. - Example in MySQL (using PDO in PHP) $stmt = $pdo->prepare('SELECT * FROM users WHERE username = :username AND password = :password'); $stmt->execute(['username' => $username, 'password' => $password]); ● Input Validation: Always validate user input by checking for expected data types, lengths, and ranges. Escaping User Input: If parameters cannot be parameterized, make sure all user input is properly escaped. Least Privilege Principle: Limit database user permissions to only those necessary to perform their tasks. Web Application Firewalls (WAF): Use WAFs to detect and block SQL injection attacks. Real-world example (ShopNest) ShopNest’s SQL Server database stores customers, products, and orders. Good indexes and clear foreign keys keep checkout queries fast and safe. Say this in the interview Define — one clear sentence (the short answer above). Example — relate it to a project like ShopNest or your real work. Trade-off — when you would not use it.

Short answer: SQL Injection is a type of attack where an attacker inserts or manipulates malicious SQL code into a query, which can compromise the database.

Explain a bit more

It usually happens when user input is improperly sanitized or validated. Prevention techniques: Use Prepared Statements/Parameterized Queries: This ensures that user input is treated as data, not executable code. - Example in MySQL (using PDO in PHP) $stmt = $pdo->prepare('SELECT * FROM users WHERE username = :username AND password = :password'); $stmt->execute(['username' => $username, 'password' => $password]); ● Input Validation: Always validate user input by checking for expected data types, lengths, and ranges. Escaping User Input: If parameters cannot be parameterized, make sure all user input is properly escaped. Least Privilege Principle: Limit database user permissions to only those necessary to perform their tasks. Web Application Firewalls (WAF): Use WAFs to detect and block SQL injection attacks.

Real-world example (ShopNest)

ShopNest’s SQL Server database stores customers, products, and orders. Good indexes and clear foreign keys keep checkout queries fast and safe.

Say this in the interview

Define — one clear sentence (the short answer above).
Example — relate it to a project like ShopNest or your real work.
Trade-off — when you would not use it.

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