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Intermediate 18 min readModule: Module 7: SQL Injection (SQLi) & Parameterization

SQL Injection (SQLi) & Parameterized Queries

Prevent catastrophic SQL injection attacks by replacing string concatenation with parameterized prepared statements.

What You Will Learn in This Lesson

  • How attackers exploit unescaped string concatenation (' OR '1'='1)
  • Why parameterized prepared statements completely eliminate SQLi
  • Object-Relational Mapping (ORM) query safety

Introduction & Core Concept

SQL Injection occurs when untrusted user input is directly concatenated into a database SQL query string, allowing attackers to manipulate the query structure.
WHY DOES THIS MATTER IN THE REAL WORLD?

A single SQL injection vulnerability can allow an attacker to bypass authentication, dump the entire user database, or delete all records.

Vulnerable vs Parameterized SQL

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// VULNERABLE (DO NOT DO THIS!):
// const query = "SELECT * FROM users WHERE email = '" + userInput + "'";
 
// SECURE (Parameterized Prepared Statement):
const query = "SELECT id, email FROM users WHERE email = $1";
const result = await db.query(query, [userInput]);

Line-by-Line Technical Breakdown

1Prepared statements compile the SQL query template first, then pass data parameters separately.

Try It Yourself (Interactive Editor)

Modify the code in real-time and click Run to test live browser output and console logs.

Intelligent Code Runner & Live Sandbox[JAVASCRIPT]
JAVASCRIPT SOURCE EDITOR
Interactive Live Code

Industry Best Practices & Professional Standards

  • Never concatenate strings into SQL queries; always use parameterized queries or type-safe ORMs.

Lesson Summary & Core Takeaways

  • Parameterized queries permanently eliminate SQL injection vulnerabilities.