Error in migration - Error: You have an error in your SQL syntax; check the manual that corresponds

Question

无法理解语法 sql 文件迁移有什么问题。请帮助：

我运行耙db:migrate

错误：

Mysql2::错误：您的 SQL 语法有误；检查与您的 MySQL 服务器版本对应的手册，了解在第 1 行的 ')' 附近使用的正确语法： UPDATE photos SET votes_count = 0, rating = 0 WHERE id NOT IN ()/home/user/myapp/appmame/db/migrate/20131110162613_recalculate_photos_rating.rb:8:在“向上”

class RecalculatePhotosRating < ActiveRecord::Migration
  def up
    if Vote.where("subject_type='Photo' and rating > 1").count > 0
      ActiveRecord::Base.connection.execute "DELETE FROM votes WHERE subject_type='Photo' AND rating <= 5"
      ActiveRecord::Base.connection.execute "UPDATE votes SET rating=1 WHERE subject_type='Photo'"
    end
    pids = Vote.where(subject_type: 'Photo').pluck(:subject_id).uniq
    ActiveRecord::Base.connection.execute "UPDATE photos SET votes_count = 0, rating = 0 WHERE id NOT IN (#{pids.join(', ')})"
    ActiveRecord::Base.connection.execute "UPDATE photos SET rating=(SELECT COUNT(*) FROM votes WHERE votes.subject_type='Photo' AND subject_id=photos.id) WHERE id IN (#{pids.join(', ')})"
    ActiveRecord::Base.connection.execute "UPDATE photos SET votes_count=(SELECT COUNT(*) FROM votes WHERE votes.subject_type='Photo' AND subject_id=photos.id) WHERE id IN (#{pids.join(', ')})"
  end

  def down
  end
end

Answer 1

您必须检查 pids 查询 returns 是否为空结果：

class RecalculatePhotosRating < ActiveRecord::Migration
  def up
    if Vote.where("subject_type='Photo' and rating > 1").count > 0
      ActiveRecord::Base.connection.execute "DELETE FROM votes WHERE subject_type='Photo' AND rating <= 5"
      ActiveRecord::Base.connection.execute "UPDATE votes SET rating=1 WHERE subject_type='Photo'"
    end
    pids = Vote.where(subject_type: 'Photo').pluck(:subject_id).uniq
    unless pids.empty?
      ActiveRecord::Base.connection.execute "UPDATE photos SET votes_count = 0, rating = 0 WHERE id NOT IN (#{pids.join(', ')})"
      ActiveRecord::Base.connection.execute "UPDATE photos SET rating=(SELECT COUNT(*) FROM votes WHERE votes.subject_type='Photo' AND subject_id=photos.id) WHERE id IN (#{pids.join(', ')})"
      ActiveRecord::Base.connection.execute "UPDATE photos SET votes_count=(SELECT COUNT(*) FROM votes WHERE votes.subject_type='Photo' AND subject_id=photos.id) WHERE id IN (#{pids.join(', ')})"
    end
  end

  def down
  end
end

Error in migration - Error: You have an error in your SQL syntax; check the manual that corresponds

Error in migration - Error: You have an error in your SQL syntax; check the manual that corresponds

mysql

ruby-on-rails

mysql2