小编Rhy*_*s0h的帖子

active我正在尝试向我的表添加新列students。

我跑去rails g migration add_active_to_students active:boolean生成这个迁移：

class AddActiveToStudents < ActiveRecord::Migration[5.0]
  def change
    add_column :students, :active, :boolean, default: true
  end
end

但是当我运行时rails db:migrate我收到此错误：

PG::DuplicateColumn：错误：关系“学生”的列“活动”已存在：ALTER TABLE“学生”添加“活动”布尔值默认“t”`

正如您所看到的，实际上没有一active列students：

create_table "students", force: :cascade do |t|
    t.integer  "club_id"
    t.string   "email"
    t.string   "address_line_1"
    t.string   "address_line_2"
    t.string   "city"
    t.string   "state"
    t.integer  "postcode"
    t.string   "phone1"
    t.string   "phone2"
    t.string   "first_name"
    t.string   "last_name"
    t.date     "dob"
    t.datetime "created_at",      null: false
    t.datetime "updated_at",      null: false
    t.string   "picture"
    t.integer  "payment_plan_id"
    t.string   "parent1" …