Complete GraphQL API Server with Schema, Resolvers & Database Integration

Using a contemporary backend framework (such as Node.js with Apollo Server or Express), develop a fully functional GraphQL API server. The following should be included in the implementation:

1. Definition of GraphQL Schemas
   • Use best practices to define types, queries, and mutations.
   • Incorporate entity relationships and input types.
2. Resolvers
   • Put resolvers in place for all queries and changes.
   • Make sure that data validation and error handling are done correctly.
3. Mutations & Queries
   • At least three sample queries and three mutations should be provided.
   • CRUD (Create, Read, Update, Delete) actions should be demonstrated.
4. Integrating Databases
   • Connect to a database, such as PostgreSQL or MongoDB.
   • Use an ORM/ODM (such as Prisma or Mongoose).
   • Add seed data and sample models.
5. Project Organization & Configuration
   • Create a scalable folder structure for your stuff.
   • Provide run instructions and installation steps.
6. The Best Methods
   • Adhere to the clean code guidelines
   • For clarity, add comments.
   • Make sure the code is maintainable and modular.

Provide the entire code as well as succinct descriptions of each area.