Connecting to Your Database | Noroff Front-end Development

Now let’s connect your Express API to the MySQL database. Create a new file called src/database.ts in your project:

import "dotenv/config";
import mysql, { Pool } from "mysql2/promise";

// Create a connection pool to manage database connections
const pool: Pool = mysql.createPool({
  host: process.env.DB_HOST,
  user: process.env.DB_USER,
  password: process.env.DB_PASSWORD,
  database: process.env.DB_NAME,
  waitForConnections: true,
  connectionLimit: 10,
  queueLimit: 0,
});

export { pool };

What this code does

import "dotenv/config" loads your environment variables.
import mysql, { Pool } imports mysql2 and the Pool type for TypeScript.
const pool: Pool explicitly types the connection pool.
mysql.createPool() creates a connection pool to your MySQL database.
process.env.DB_HOST etc. use your database credentials from the .env file.
The pool automatically manages database connections for better performance.

TypeScript note

We import the Pool type to demonstrate TypeScript usage. Going forward, we’ll let TypeScript infer types to keep database code clean and focused on SQL concepts.

Why use a connection pool?

Instead of creating a new connection for every API request (which is slow), the pool maintains a set of reusable connections. This improves performance and handles connection cleanup automatically, so you don’t need to close connections on each request.

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