How to connect nodejs to database

Steps to connect to a database in Node.js: Install the MySQL, MongoDB or PostgreSQL package. Create a database connection object. Open a database connection and handle connection errors.

How to connect to the database in Node.js

Connect to the MySQL database

To connect to a MySQL database, you can use the following steps:

1. InstallmysqlPackage:npm install mysql
2. Create a database Connection object:

const mysql = require('mysql'); const connection = mysql.createConnection({ host: 'localhost', user: 'username', password: 'password', database: 'database_name' });

3. Open database connection:

connection.connect((err) => { if (err) { console.log('Error connecting to database:', err); return; } console.log('Connected to MySQL database'); });

Connect to MongoDB database

To connect to MongoDB database, You can use the following steps:

1. InstallmongodbPackage:npm install mongodb
2. Create a database connection object:

const mongo = require('mongodb'); const MongoClient = mongo.MongoClient; const url = 'mongodb://localhost:27017';

3. Open database connection:

MongoClient.connect(url, (err, client) => { if (err) { console.log('Error connecting to database:', err); return; } console.log('Connected to MongoDB database'); // 使用 client 对象进行数据库操作 });

Connect to PostgreSQL database

To connect to PostgreSQL database, you can use the following steps:

1. InstallpgPackage:npm install pg
2. Create a database connection object:

const pg = require('pg'); const connectionString = 'postgres://username:password@localhost:5432/database_name'; const client = new pg.Client(connectionString);

3. Open database connection:

client.connect((err) => { if (err) { console.log('Error connecting to database:', err); return; } console.log('Connected to PostgreSQL database'); });

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