MySQLにアクセスしてデータを取得し表示する

app.rb

require 'sinatra'
require 'sinatra/reloader'
require 'mysql2'
require 'mysql2-cs-bind'

# Mysqlドライバの設定
db = Mysql2::Client.new(
  host: 'localhost',
  port: 3306,
  username: 'root',
  password: '',
  database: 'sample',
  reconnect: true,
)

set :public_folder, File.dirname(__FILE__) + '/public'

get '/' do
  @title = 'hoge'

  erb :index
end

get '/hello' do
  erb :hello
end

get '/fruits/' do
  @fruits = ['Apple', 'Banana', 'Lemon', 'Meron', 'Strawberry']
  erb :fruits
end

get '/infos' do
  # @infos = [{
  #   name: 'saboyuta',
  #   age: 30
  # },{
  #   name: 'gakeo',
  #   age: 27
  # }]
  @infos = db.xquery("SELECT * From infos")
  erb :infos
end

get '/infos/:id' do |id|
  # @info = [{
  #   name: 'saboyuta',
  #   age: 30
  # }]
  @info = db.xquery("SELECT * From infos WHERE id = #{id}").to_a.first
  erb :info
end

info.erb

<h1>Info</h1>

<p>名前は、<%= @info["name"] %></p>
<p>年齢は、<%= @info["age"] %></p>

infos.erb

<h1>Info</h1>

<% @infos.each do |info| %>
  <p>名前は、<%= info["name"] %></p>
  <p>年齢は、<%= info["age"] %></p>
<% end %>