2. Connecting to a database

How to Connect

With pg, you use a connection pool or client to connect to a PostgreSQL database. Similarly, Mongoose uses a connect method with a connection string to establish communication with a MongoDB instance.

• Example Connection (PostgreSQL with pg):

  const { Pool } = require('pg');
  const pool = new Pool({
    user: 'username',
    host: 'localhost',
    database: 'schoolDB',
    password: 'password',
    port: 5432,
  });
  
  pool.connect()
    .then(() => console.log('Connected to PostgreSQL'))
    .catch(err => console.error('Connection error', err));

• Example Connection (MongoDB with Mongoose):

  const mongoose = require('mongoose');
  
  mongoose.connect('mongodb://localhost:27017/schoolDB', {
    useNewUrlParser: true,
    useUnifiedTopology: true,
  })
  .then(() => console.log('Connected to MongoDB'))
  .catch(err => console.error('Connection error', err));

Key Differences

• Connection String: MongoDB uses a URI format (mongodb://localhost:27017/databaseName), while PostgreSQL uses credentials passed into a pg client or pool.
• Built-in Options: Mongoose includes features like automatic retries and deprecation warnings when connecting, simplifying connection management.