Node.js connects to many databases. This chapter covers MongoDB (NoSQL) and SQL with Prisma.

MongoDB with Mongoose 

  npm install mongoose
  
  import mongoose from 'mongoose';

await mongoose.connect(process.env.DATABASE_URL);

const userSchema = new mongoose.Schema({
    name: { type: String, required: true },
    email: { type: String, required: true, unique: true },
    createdAt: { type: Date, default: Date.now }
});

const User = mongoose.model('User', userSchema);

// Create
const user = await User.create({ name: 'Alice', email: '[email protected]' });

// Read
const users = await User.find();
const one = await User.findById(user._id);
const byEmail = await User.findOne({ email: '[email protected]' });

// Update
await User.findByIdAndUpdate(user._id, { name: 'Alice Smith' });

// Delete
await User.findByIdAndDelete(user._id);

Express + Mongoose 

  app.get('/api/users', async (req, res) => {
    const users = await User.find().select('-__v');
    res.json(users);
});

app.post('/api/users', async (req, res) => {
    try {
        const user = await User.create(req.body);
        res.status(201).json(user);
    } catch (err) {
        res.status(400).json({ error: err.message });
    }
});

SQL with Prisma 

  npm install prisma @prisma/client
npx prisma init

schema.prisma:

  model User {
  id        Int      @id @default(autoincrement())
  name      String
  email     String   @unique
  createdAt DateTime @default(now())
}
  
  npx prisma migrate dev --name init
  
  import { PrismaClient } from '@prisma/client';
const prisma = new PrismaClient();

// Create
const user = await prisma.user.create({
    data: { name: 'Bob', email: '[email protected]' }
});

// Read
const users = await prisma.user.findMany();
const one = await prisma.user.findUnique({ where: { id: 1 } });

// Update
await prisma.user.update({
    where: { id: 1 },
    data: { name: 'Robert' }
});

// Delete
await prisma.user.delete({ where: { id: 1 } });

Connection Best Practices

  • Store connection strings in environment variables
  • Handle connection errors on startup
  • Close connections gracefully on shutdown:
  process.on('SIGINT', async () => {
    await mongoose.connection.close();
    process.exit(0);
});

Choosing a Database

Use MongoDB when Use SQL when
Flexible schema Strict relationships
Document-oriented data Transactions critical
Rapid prototyping Complex queries/joins

Both work excellently with Node.js — choose based on your data model, not hype.