update

Gemfile

@@ -9,8 +9,8 @@ end
 # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
 gem 'rails', '~> 5.1.0'
 # Use mysql as the database for Active Record
-gem 'mysql2', '>= 0.3.18', '< 0.5'
-#gem 'pg'
+#gem 'mysql2', '>= 0.3.18', '< 0.5'
+gem 'pg'
 # Use Puma as the app server
 gem 'puma', '~> 3.0'
 # Use SCSS for stylesheets

Gemfile.lock

@@ -96,11 +96,11 @@ GEM
     mini_portile2 (2.1.0)
     minitest (5.10.2)
     multi_json (1.12.1)
-    mysql2 (0.4.6)
     nio4r (2.0.0)
     nokogiri (1.7.2)
       mini_portile2 (~> 2.1.0)
     pdf-core (0.7.0)
+    pg (0.20.0)
     prawn (2.2.2)
       pdf-core (~> 0.7.0)
       ttfunk (~> 1.5)
@@ -232,7 +232,7 @@ DEPENDENCIES
   jbuilder (~> 2.5)
   jquery-rails
   listen (~> 3.0.5)
-  mysql2 (>= 0.3.18, < 0.5)
+  pg
   prawn
   prawn-table
   puma (~> 3.0)