add index

db/migrate/20191126082849_create_users.rb

@@ -5,8 +5,8 @@ class CreateUsers < ActiveRecord::Migration[6.0]
       t.string :last_name
 
       ## Database authenticatable
-      t.string :email, null: false, unique: true default: ""
-      t.string :username, unique: true
+      t.string :email, null: false, default: ""
+      t.string :username
       t.string :encrypted_password, null: false, default: ""
 
       ## Recoverable
@@ -44,6 +44,7 @@ class CreateUsers < ActiveRecord::Migration[6.0]
 
     add_index :users, :email, unique: true
     add_index :users, :reset_password_token, unique: true
+    add_index :users, :username, unique: true
     # add_index :users, :confirmation_token,   unique: true
     # add_index :users, :unlock_token,         unique: true
   end

db/schema.rb

@@ -108,6 +108,7 @@ ActiveRecord::Schema.define(version: 2019_11_26_083335) do
     t.datetime "updated_at", precision: 6, null: false
     t.index ["email"], name: "index_users_on_email", unique: true
     t.index ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true
+    t.index ["username"], name: "index_users_on_username", unique: true
   end
 
   add_foreign_key "city_jobs", "cities"