Apache CouchDB

// Connect to CouchDB
const nano = require('nano')('http://localhost:5984');
const db = nano.use('users');

// Create a document
const user = {
  _id: 'user123',
  name: 'John Doe',
  email: 'john@example.com',
  created: new Date().toISOString()
};

await db.insert(user);

// Read a document
const doc = await db.get('user123');
console.log(doc.name); // 'John Doe'

// Update a document
doc.last_login = new Date().toISOString();
await db.insert(doc);

// Create a MapReduce view
const designDoc = {
  _id: '_design/users',
  views: {
    by_email: {
      map: function(doc) {
        if (doc.email) {
          emit(doc.email, doc);
        }
      }
    }
  }
};

await db.insert(designDoc);

// Query the view
const result = await db.view('users', 'by_email', {
  key: 'john@example.com'
});