1) Create new Ruby on Rails application

Ruby Verions 2.6.2
Rails verions 5.1.4

rails new learnexa_api -d mysql

2) Add GraphQL in gem file

gem 'graphql', '~>1.8.10'

bundle install

3) Add GraphQL to a Rails app

rails g graphql:install

bundle install

4) Add existing learnexa db in database.yml file

default: &default
  adapter: mysql2
  encoding: utf8
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  username: root
  password: root
  socket: /var/run/mysqld/mysqld.sock

development:
  <<: *default
  database: learnexa_db

4) Start rails server Open localhost:3000/graphiql to gew