Connect to TiDB with mysql2 in Next.js

TiDB is a MySQL-compatible database, and mysql2 is a popular open-source driver for Node.js.

In this tutorial, you can learn how to use TiDB and mysql2 in Next.js to accomplish the following tasks:

• Set up your environment.
• Connect to your TiDB cluster using mysql2.
• Build and run your application. Optionally, you can find sample code snippets for basic CRUD operations.

Prerequisites

To complete this tutorial, you need:

• Node.js 18 or later.
• Git.
• A TiDB cluster.

If you don't have a TiDB cluster, you can create one as follows:

• (Recommended) Follow Creating a TiDB Serverless cluster to create your own TiDB Cloud cluster.
• Follow Deploy a local test TiDB cluster or Deploy a production TiDB cluster to create a local cluster.

Run the sample app to connect to TiDB

This section demonstrates how to run the sample application code and connect to TiDB.

Step 1: Clone the sample app repository

Run the following commands in your terminal window to clone the sample code repository:

git clone git@github.com:tidb-samples/tidb-nextjs-vercel-quickstart.git
cd tidb-nextjs-vercel-quickstart

Step 2: Install dependencies

Run the following command to install the required packages (including mysql2) for the sample app:

npm install

Step 3: Configure connection information

Connect to your TiDB cluster depending on the TiDB deployment option you've selected.

• TiDB Serverless
• TiDB Self-Hosted

Step 4: Run the code and check the result

1. Start the application:

   npm run dev
   

2. Open your browser and visit http://localhost:3000. (Check your terminal for the actual port number, and the default is 3000.)

3. Click RUN SQL to execute the sample code.

4. Check the output in the terminal. If the output is similar to the following, the connection is successful:

   {
     "results": [
       {
         "Hello World": "Hello World"
       }
     ]
   }
   

Sample code snippets

You can refer to the following sample code snippets to complete your own application development.

For complete sample code and how to run it, check out the tidb-nextjs-vercel-quickstart repository.

Connect to TiDB

The following code establish a connection to TiDB with options defined in the environment variables:

// src/lib/tidb.js
import mysql from 'mysql2';

let pool = null;

export function connect() {
  return mysql.createPool({
    host: process.env.TIDB_HOST, // TiDB host, for example: {gateway-region}.aws.tidbcloud.com
    port: process.env.TIDB_PORT || 4000, // TiDB port, default: 4000
    user: process.env.TIDB_USER, // TiDB user, for example: {prefix}.root
    password: process.env.TIDB_PASSWORD, // The password of TiDB user.
    database: process.env.TIDB_DATABASE || 'test', // TiDB database name, default: test
    ssl: {
      minVersion: 'TLSv1.2',
      rejectUnauthorized: true,
    },
    connectionLimit: 1, // Setting connectionLimit to "1" in a serverless function environment optimizes resource usage, reduces costs, ensures connection stability, and enables seamless scalability.
    maxIdle: 1, // max idle connections, the default value is the same as `connectionLimit`
    enableKeepAlive: true,
  });
}

export function getPool() {
  if (!pool) {
    pool = createPool();
  }
  return pool;
}

Insert data

The following query creates a single Player record and returns a ResultSetHeader object:

const [rsh] = await pool.query('INSERT INTO players (coins, goods) VALUES (?, ?);', [100, 100]);
console.log(rsh.insertId);

For more information, refer to Insert data.

Query data

The following query returns a single Player record by ID 1:

const [rows] = await pool.query('SELECT id, coins, goods FROM players WHERE id = ?;', [1]);
console.log(rows[0]);

For more information, refer to Query data.

Update data

The following query adds 50 coins and 50 goods to the Player with ID 1:

const [rsh] = await pool.query(
    'UPDATE players SET coins = coins + ?, goods = goods + ? WHERE id = ?;',
    [50, 50, 1]
);
console.log(rsh.affectedRows);

For more information, refer to Update data.

Delete data

The following query deletes the Player record with ID 1:

const [rsh] = await pool.query('DELETE FROM players WHERE id = ?;', [1]);
console.log(rsh.affectedRows);

For more information, refer to Delete data.

Useful notes

• Using connection pools to manage database connections can reduce the performance overhead caused by frequently establishing and destroying connections.
• To avoid SQL injection, it is recommended to use prepared statements.
• In scenarios where there are not many complex SQL statements involved, using ORM frameworks like Sequelize, TypeORM, or Prisma can greatly improve development efficiency.

Next steps

• For more details on how to build a complex application with ORM and Next.js, see our Bookshop Demo.
• Learn more usage of node-mysql2 driver from the documentation of node-mysql2.
• Learn the best practices for TiDB application development with the chapters in the Developer guide, such as Insert data, Update data, Delete data, Single table reading, Transactions, and SQL performance optimization.
• Learn through the professional TiDB developer courses and earn TiDB certifications after passing the exam.

Need help?

Ask questions on TiDB Community, or create a support ticket.