我是一名初学者，正在阅读 Michael Hartl 的 Ruby on Rails 教程。我正在尝试在 Heroku 控制台中创建一个用户：这是我关注的 tut：(35:21)
irb(main):001:0> User.create!(:name => "Example User", :email => "example@example.com", :password => "foobar", :password_confirmation => "foobar")
我收到这个错误！我不明白PGError: ERROR: relation "users" does not exist
PGError: ERROR: relation "users" does not exist
LINE 5: WHERE a.attrelid = '"users"'::regclass
^
: SELECT a.attname, format_type(a.atttypid, a.atttypmod),
pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod
FROM pg_attribute a LEFT JOIN pg_attrdef d
ON a.attrelid = d.adrelid AND a.attnum = d.adnum
WHERE a.attrelid = '"users"'::regclass
AND a.attnum > 0 AND NOT a.attisdropped
ORDER BY a.attnum
ActiveRecord::StatementInvalid: PGError: ERROR: relation "users" does not exist
LINE 5: WHERE a.attrelid = '"users"'::regclass
^
: SELECT a.attname, format_type(a.atttypid, a.atttypmod),
pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod
FROM pg_attribute a LEFT JOIN pg_attrdef d
ON a.attrelid = d.adrelid AND a.attnum = d.adnum
WHERE a.attrelid = '"users"'::regclass
AND a.attnum > 0 AND NOT a.attisdropped
ORDER BY a.attnum
from /app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/postgresql_adapter.rb:1161:in `async_exec'
from /app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/postgresql_adapter.rb:1161:in `exec_no_cache'
from /app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/postgresql_adapter.rb:660:in `block in exec_query'
from /app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract_adapter.rb:280:in `block in log'
from /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.13/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
from /app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract_adapter.rb:275:in `log'
from /app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/postgresql_adapter.rb:659:in `exec_query'
from /app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/postgresql_adapter.rb:1286:in `column_definitions'
from /app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/postgresql_adapter.rb:855:in `columns'
from /app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/schema_cache.rb:12:in `block in initialize'
from /app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/model_schema.rb:228:in `yield'
from /app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/model_schema.rb:228:in `default'
from /app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/model_schema.rb:228:in `columns'
from /app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/model_schema.rb:243:in `column_defaults'
from /app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/base.rb:482:in `initialize'
from /app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/validations.rb:39:in `new'
from /app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/validations.rb:39:in `create!'
from (irb):1
from /app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.13/lib/rails/commands/console.rb:47:in `start'
from /app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.13/lib/rails/commands/console.rb:8:in `start'
from /app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.13/lib/rails/commands.rb:41:in `<top (required)>'
from script/rails:6:in `require'