How to connect nodejs to database

Connect to the database, Node.js provides a variety of database connector packages such as MySQL, PostgreSQL, MongoDB and Redis. The connection steps include: 1. Install the corresponding connector package; 2. Create a connection pool to maintain reusable connections; 3. Establish a connection with the database. Note: The operation is asynchronous and errors need to be handled to ensure security and optimize performance.

How to connect to the database using Node.js

Connect to the database

Node.js provides a variety of database connectors that allow you to connect to various types of databases. The steps to connect to the database are as follows:

1. Install the corresponding connector package.
2. Create a connection pool to maintain reusable database connections.
3. Establish a connection to the database.

Connector packages

The most popular Node.js database connector packages include:

• [MySQL](https ://www.npmjs.com/package/mysql)
• [PostgreSQL](https://www.npmjs.com/package/pg)
• [MongoDB](https:/ /www.npmjs.com/package/mongodb)
• [Redis](https://www.npmjs.com/package/redis)

Create a connection pool

Connection pooling maintains a set of pre-established database connections in the application. This helps reduce the overhead of connection establishment and destruction and improves performance.

To create a connection pool, you can use the following code:

<code class="javascript">const mysql = require('mysql');

const pool = mysql.createPool({
  host: 'localhost',
  user: 'root',
  password: '',
  database: 'my_database'
});</code>

Establish a connection

After using the connection pool, you can obtain a connection in the following ways :

<code class="javascript">pool.getConnection((err, connection) => {
  // 使用连接执行查询
});</code>

After the connection is used, it needs to be released back to the connection pool:

<code class="javascript">connection.release();</code>

Other notes

• Asynchronous operation: Database operations are typically asynchronous, meaning they are executed in the background and trigger a callback function when completed.
• Error handling: Always handle errors in connections and queries.
• Security: Protect database credentials and use SQL prepared statements to prevent SQL injection attacks.
• Performance optimization: Use indexes, caches and connection pools to improve database performance.

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