Preventing SQL Injection in Node.js with pg and Other Programming Languages

What is sql injections

SQL injection is one of the most common and very dangerous web application vulnerabilities, staying on top of the OWASP Top 10.

This blogs takes to you into some basic technical analysis of SQL Injections prevention techniques, focused especially on Node.js PostgreSQL (PG) packages.

while casting a wide net around other programming languages. New coding patterns are discussed, from the offensive (inducing vulnerabilities) to the defensive (protecting the application), along with advanced architectural controls and testing methodologies.

The vulnerable SQL injections code

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SQL Injection Mechanics and Impact

SQL injection arises when unsafe query data are concatenated to SQL queries performing malfunctions to the query logic by an attacker. These gaining unauthorized access to the data to total compromise of a database. These result from two major lapses:

1. Failure to check/sanitize user input.
2. Unsafe query building: using direct embedding of user input in SQL statements without proper parameterize.

The current-day database systems such as PostgreSQL do offer a number of defense mechanisms; their effectiveness depends on their correct implementation. Recent studies show that 42 per cent of web applications still present at least one SQLi vulnerability, mostly caused by misconfiguration ORM layers or improper use of prepared statements.

so when you are handling with the sql query please be aware even a single mistake can cause sql injections in you applications

Offensive and defencive Patterns: Common Vulnerability

Node.js PostgreSQL Anti-Patterns

Unsafe String Concatenation

// UNSAFE: Direct string interpolation
const query = `SELECT * FROM users WHERE email = '${email}'`;
client.query(query, (err, res) => { ... });

Attackers can inject ' OR 1=1 -- to bypass authentication.

Dangerous Dynamic Schema Handling

// UNSAFE: User-controlled table/column names
const orderBy = req.query.sort || 'id';
const query = `SELECT * FROM products ORDER BY ${orderBy}`;

Allows injection of subqueries via sort parameters.

Cross-Language Vulnerability Examples

PHP (PDO Misuse)

// UNSAFE: Placeholder bypass
$stmt = $pdo->prepare("SELECT * FROM users WHERE id = " . $_GET['id']);
$stmt->execute();

Python (SQLAlchemy Raw SQL)

# UNSAFE: Textual SQL with interpolation
query = text(f"SELECT * FROM orders WHERE status = '{status}'")
result = conn.execute(query)

Defensive Strategies for Node.js PostgreSQL

1. Parameterized Queries with node-postgres

// SAFE: Parameterized query
const query = 'SELECT * FROM users WHERE email = $1';
const values = [email];
client.query(query, values, (err, res) => { ... });

Why is this safe? The $1 placeholder ensures the input is handled as a string value, preventing SQL injection. The PG driver automatically handles type-safe escaping and prevents query structure alteration.

2.Leverage Prepared Statements

Prepared statements enhance security by precompiling SQL statements, ensuring queries remain structured before execution.

async function getUserSecure(email) {
    const client = await pool.connect();
    try {
        const query = {
            text: 'SELECT * FROM users WHERE email = $1',
            values: [email],
        };
        const result = await client.query(query);
        return result.rows;
    } finally {
        client.release();
    }
}

3. Strict Input Validation with Zod

import { z } from 'zod';

const EmailSchema = z.string().email().max(254);
const safeEmail = EmailSchema.parse(rawInput);

Enforces email format and length constraints before query execution.

4. Query Construction with Knex.js

const safeQuery = knex('users')
  .where({
    email: rawInputEmail,
    status: 'active'
  })
  .orderBy('created_at', 'desc');

Knex generates parameterized SQL while preventing schema injection through object notation.

5. Advanced ORM Protection with Sequelize

const User = sequelize.define('user', { ... });

// SAFE: Model-based querying
User.findAll({
  where: {
    email: {
      [Op.eq]: sanitizedEmail
    }
  }
});

Sequelize applies type-aware escaping and supports read-only transactions for additional protection.

Cross-Language Defense Mechanisms

PHP: PDO Prepared Statements

$stmt = $pdo->prepare("SELECT * FROM users WHERE id = :id");
$stmt->execute(['id' => $userId]);

Python: SQLAlchemy Core

stmt = select([users]).where(users.c.email == bindparam('email'))
conn.execute(stmt, {'email': validated_email})

Universal Best Practices for Prevention of SQL Injection

1. Across all languages and frameworks, the following best practices must be incorporated so please follow those documentations to implement on you own applicaitons
2. Always use parameterized queries or prepared statements this will not attacker to inject the SQL queries on your applications.
3. Don't concatenate user input directly into SQL queries, but use some validation tools appropriately, like ZOD for nodejs, to validate every user's input from the payload before an insert/select into the database.
4. Don't concatenate user input directly into SQL queries, but use some validation tools appropriately, like ZOD for nodejs, to validate every user's input from the payload before an insert/select into the database.
5. Least privilege classes for database users: please create new users and give to them just what they require (do not give delete access so that data loss is avoided unless it is absolutely necessary).
6. Monitor database logs for unusual querying styles: Keep the logs updated with daily questioning types so that they are vigilantly checked for the signature of those who use SQL injection techniques against the databases on pseudonyms.
7. Update database drivers and application dependencies regularly.
8. Deploy Web Application Firewalls (WAF) to filter malicious requests, Create some rules in your firewall to prevent the SQL injections attacks.
9. Enforce a rigorous set of validation rules, user zod for nodejs to validate user inputs.
10. Encrypt sensitive data to minimize its exposure, encrypt sensitive data in databases so you know that its of super confidential nature to go public like number cards, email, mobile numbers Etc....