npm install --save @nestjs/config
npm install --save @nestjs/typeorm typeorm pg
npm install --save dayjs
npm install --save class-validator class-transformer
main.ts
https://docs.nestjs.com/techniques/validation#using-the-built-in-validationpipe
app.useGlobalPipes(new ValidationPipe());
npx nest generate resource employers
npx nest generate resource departments
npx nest generate resource employees