SQL Security (Injection Prevention) 🛡️¶

Mentor's Note: The most dangerous weapon against a database is a simple text box. If you aren't careful, a hacker can type SQL code into your "Login" box and delete your whole database. This is called SQL Injection. ⚠️

🌟 The Scenario: The Fake Ticket 🎫¶

Imagine a bus conductor who only reads the text on a ticket. - Normal Passenger: "Ticket for Rustompura." (Conductor takes him there). ✅ - Malicious Passenger: "Ticket for Rustompura... AND then DRIVE THE BUS TO MY HOUSE!" - The Result: If the conductor just follows instructions blindly, the bus is hijacked! 🚌💨

💻 1. What is SQL Injection?¶

It happens when user input is combined directly with a query.

-- ❌ DANGEROUS CODE (Vulnerable)
-- User types: ' OR 1=1 --
query = "SELECT * FROM users WHERE username = '" + user_input + "'";

-- Becomes:
SELECT * FROM users WHERE username = '' OR 1=1 --';
-- Result: Logged in as EVERYONE! 🔓

🛡️ 2. The Solution: Prepared Statements¶

Instead of combining strings, we use Placeholders (?). The database treats the input as "Data Only," never as "Code."

-- ✅ SECURE CODE (Parameterized)
query = "SELECT * FROM users WHERE username = ?";
-- User input is safely swapped into the ? marker.

🎨 Visual Logic: The Safety Shield¶

graph TD
    A[User Input ⌨️] --> B{Safety Check}
    B -- "Direct String" --> C[SQL Injection Risk 💣]
    B -- "Parameterized" --> D[Secure Query Execution 🛡️]
    D --> E[(Database 🗄️)]

📋 3. Top Security Best Practices¶

Least Privilege: Give the application "Read-Only" access if it doesn't need to "Delete." 🔑
Input Validation: If you expect a "Phone Number," don't accept letters! 🔢
Encrypted Passwords: NEVER store passwords in plain text. Use Hashing. 🔒
Hide Errors: Don't show technical SQL errors to the end-user. Show a friendly "Something went wrong" message. 🤫

💡 Interview Tip 👔¶

"If an interviewer asks 'How do you stop SQL Injection?', the first word out of your mouth should be: Prepared Statements (or Parameterized Queries)!"