Sequelize supports a wide range of databases, including PostgreSQL, MySQL, MariaDB, SQLite, and Microsoft SQL Server. Its versatility makes it a popular choice for projects that need to work with multiple database systems or require advanced features like migrations and transactions.

Objection.js also supports PostgreSQL, MySQL, and SQLite, providing a robust foundation for working with relational databases. Its integration with Knex.js allows for advanced query building and customization, making it ideal for applications with complex data models.

Bookshelf.js supports PostgreSQL, MySQL, and SQLite, leveraging Knex.js for database interactions. It is suitable for projects that require a relational database with support for complex queries and relationships.

Waterline supports various databases through adapters, including SQL databases (PostgreSQL, MySQL, SQLite) and NoSQL databases (MongoDB). This flexibility makes it suitable for applications that need to interact with different types of data stores.

Sequelize offers a comprehensive set of querying features, including support for complex queries, transactions, and migrations. It provides a rich API for filtering, sorting, and aggregating data, as well as support for eager and lazy loading of relationships. Sequelize is well-suited for applications that require advanced querying capabilities and a high level of customization.

Objection.js excels in querying capabilities, offering a powerful and flexible API for building complex SQL queries. It supports eager and lazy loading, as well as advanced features like subqueries, transactions, and custom query builders. Objection.js is designed for developers who need fine-grained control over their queries while still enjoying an object-oriented interface.

Bookshelf.js provides a simple and intuitive API for querying data, with support for eager and lazy loading of relationships. It allows for chaining queries and supports basic filtering, sorting, and pagination. However, it may not be as feature-rich as some other ORMs when it comes to advanced querying capabilities.

Waterline provides a simple and consistent querying API, but it may not be as powerful as some other ORMs in terms of advanced querying features. It supports basic filtering, sorting, and pagination, as well as querying across relationships. Waterline's strength lies in its simplicity and ease of use, making it a good choice for projects that do not require highly complex queries.

Sequelize has extensive support for relationship management, allowing developers to define and manage various types of relationships between models. It supports one-to-one, one-to-many, and many-to-many relationships, and provides a rich set of features for managing these relationships, including cascading deletes, custom join tables, and more. Sequelize's relationship management capabilities are well-documented and highly customizable, making it suitable for applications with complex data structures.

Objection.js also provides excellent support for relationship management, with a focus on flexibility and performance. It supports one-to-one, one-to-many, and many-to-many relationships, and allows for custom relationship types and query builders. Objection.js is designed to handle complex relationships efficiently, making it a great choice for applications with intricate data models.

Bookshelf.js offers robust support for managing relationships between models, including one-to-one, one-to-many, and many-to-many relationships. It provides a simple API for defining and querying relationships, as well as support for eager and lazy loading. Bookshelf.js is particularly strong in handling complex relationships and provides good documentation on how to use these features effectively.

Waterline provides basic support for managing relationships between models, including one-to-one, one-to-many, and many-to-many relationships. It uses a simple and intuitive API for defining and querying relationships, but it may not be as feature-rich or flexible as some other ORMs in handling complex relationships. Waterline's relationship management is straightforward and easy to use, making it suitable for projects that require simple relationship handling without a lot of complexity.

Sequelize includes a built-in migration system, making it easy to manage database schema changes over time. It provides tools for creating, running, and rolling back migrations, as well as support for seeding data. Sequelize's migration features are well-integrated and documented, making it a comprehensive solution for projects that require structured schema management.

Objection.js also does not provide built-in migration tools, as it is designed to work with Knex.js, which handles migrations and schema management. Developers can use Knex.js migrations alongside Objection.js models, allowing for a clear separation of concerns between data modeling and schema management.

Bookshelf.js does not include built-in support for migrations or schema management, as it relies on Knex.js for these features. Developers will need to use Knex.js directly or integrate another migration tool into their project. This approach allows for flexibility but means that migration management is not handled by Bookshelf.js itself.

Waterline does not provide built-in migration tools, as it is designed to work with various database adapters that may have different migration capabilities. Developers will need to implement their own migration strategy or use a separate migration tool alongside Waterline. This lack of built-in migration support means that schema management is not a core feature of Waterline.

Sequelize is known for its rich feature set and flexibility, but it can be overwhelming for beginners due to its complexity. The documentation is extensive, and there are many tutorials and resources available to help new users get up to speed. Sequelize provides a lot of functionality out of the box, including migrations, validations, and hooks, which can make it easier to build robust applications. However, the learning curve may be steep for those who are new to ORMs or relational databases. Overall, Sequelize is a powerful tool that is well-suited for large applications that require a comprehensive ORM solution.

Example Code:

const { Sequelize, DataTypes } = require('sequelize');

// Initialize Sequelize
const sequelize = new Sequelize('sqlite::memory:');

// Define a simple model
const User = sequelize.define('User', {
  name: { type: DataTypes.STRING, allowNull: false },
});

// Sync the model with the database
sequelize.sync().then(() => {
  // Create a new user
  return User.create({ name: 'Alice' });
}).then((user) => {
  console.log('User created:', user);
  // Fetch the user by ID
  return User.findByPk(user.id);
}).then((fetchedUser) => {
  console.log('Fetched user:', fetchedUser);
});

Objection.js is designed to be easy to use while providing powerful features for more advanced users. Its API is straightforward, and it leverages the power of Knex.js for query building, which makes it familiar to developers who have used Knex before. The documentation is comprehensive, and the library is well-structured, making it easy to understand and use for both simple and complex data models. Objection.js strikes a good balance between usability and flexibility, making it suitable for a wide range of projects, from small applications to large-scale systems that require more control over their data interactions.

Example Code:

const { Model } = require('objection');

// Initialize Knex
const knex = require('knex')({
  client: 'sqlite3',
  connection: {
    filename: './data.db',
  },
});
Model.knex(knex);

// Define a simple model
class User extends Model {
  static get tableName() {
    return 'users';
  }
}

// Create a new user
User.query().insert({ name: 'Jane Doe' }).then((user) => {
  console.log('User created:', user);
});

// Fetch a user by ID
User.query().findById(1).then((user) => {
  console.log('Fetched user:', user);
});

Bookshelf.js is known for its simplicity and ease of use, especially for developers familiar with Backbone.js. Its API is intuitive, and the documentation is clear, making it easy to get started with basic CRUD operations and relationship management. However, some users may find the lack of built-in features like migrations and schema management to be a limitation, requiring additional tools or libraries to fill the gaps. Overall, Bookshelf.js strikes a good balance between simplicity and functionality, making it a great choice for small to medium-sized projects that do not require overly complex data modeling.

Example Code:

const Bookshelf = require('bookshelf')(knex);

// Define a simple model
const User = Bookshelf.model('User', {
  tableName: 'users',
});

// Create a new user
User.forge({ name: 'John Doe' }).save().then((user) => {
  console.log('User created:', user);
});

// Fetch a user by ID
User.where({ id: 1 }).fetch().then((user) => {
  console.log('Fetched user:', user);
});

Waterline is designed to be simple and easy to use, especially for applications built on the Sails.js framework. Its API is straightforward, and it provides a consistent interface for working with different types of data stores. However, Waterline may lack some of the advanced features and flexibility found in more mature ORMs like Sequelize or Objection.js. The documentation is decent, but users may need to rely on community resources and examples to fully understand how to leverage all of Waterline's capabilities. Overall, Waterline is a good choice for projects that prioritize simplicity and need to work with multiple types of data stores without requiring a lot of complexity.

Example Code:

const Waterline = require('waterline');
const Adapter = require('sails-postgresql'); // Example adapter

// Create a Waterline instance
const waterline = new Waterline();

// Define a simple model
const userModel = {
  identity: 'user',
  datastore: 'default',
  attributes: {
    name: { type: 'string', required: true },
  },
};

// Add the model to Waterline
waterline.loadCollection(Waterline.Collection.extend(userModel));

// Initialize Waterline
waterline.initialize({ adapters: { postgres: Adapter }, datastores: { default: { adapter: 'postgres' } } }, (err, ontology) => {
  if (err) throw err;

  // Create a new user
  const User = ontology.collections.user;
  User.create({ name: 'Bob' }).then((user) => {
    console.log('User created:', user);
  });
});