Knex.js: Knex.js is a SQL query builder for Node.js that allows you to build SQL queries using a fluent and flexible JavaScript syntax. It's often used to interact with relational databases and provides features like query building, migrations, and connection pooling.

Prisma: Prisma is an open-source database toolkit that provides an Object-Relational Mapping (ORM) layer for working with databases. Prisma simplifies database access by generating type-safe and efficient query builders for your application. It supports multiple databases and offers powerful features like migrations, schema management, and real-time data synchronization.

Query Building:

Knex.js: Knex.js provides a flexible and powerful query builder that allows you to construct complex SQL queries using JavaScript methods. It's well-suited for cases where you need fine-grained control over your queries.

Example: Building a simple query to retrieve all users from a hypothetical "users" table using Knex.js:

const users = await knex('users').select('*');

Prisma: Prisma generates a type-safe query builder based on your database schema. This eliminates the need to write raw SQL queries and provides auto-completion and validation while writing queries.

Example: Using Prisma to retrieve all users:

const users = await prisma.user.findMany();

Data Modeling:

Knex.js: With Knex.js, you manually define your database schema and create migration files to manage changes to your schema over time.

Prisma: Prisma offers a powerful schema definition language that allows you to define your data models. It can automatically generate migrations based on changes you make to your schema.

Migrations:

Knex.js: Knex.js supports migrations to manage changes to your database schema. You write migration files manually to define schema changes and apply them using commands.

Prisma: Prisma's migrations work similarly, but Prisma can also automatically generate migrations for you based on your schema changes, saving you time and effort.

Performance:

Knex.js: Since Knex.js allows you to write raw SQL queries, you have more control over the performance optimization of your queries. However, this might require more effort in writing efficient queries.

Prisma: Prisma's query builder is optimized for performance out of the box, and it generates efficient queries. It also provides tools for profiling and analyzing query performance.

Ecosystem and Community:

Knex.js: Knex.js has been around for a longer time and has a well-established community and ecosystem of plugins and extensions.

Prisma: Prisma is newer and rapidly growing. Its focus on modern development patterns, type-safety, and features like real-time data synchronization make it attractive for many developers.

In conclusion, the choice between Knex.js and Prisma depends on your project's needs. Knex.js is suitable if you prefer writing raw SQL queries and require maximum control over your queries. Prisma is a better fit if you value type safety, automatic query generation, and modern development practices.