title: can't run migrations. Table doesn't exists
body: <p>I am trying to set up a Rails app in new workstation. But when I try to run the migrations it throws error.</p>
  
  <pre><code>**rake aborted!
  ActiveRecord::StatementInvalid: Mysql2::Error: Table 'test_rb.roles' doesn't exist: SHOW FULL FIELDS FROM `roles`**
  /home/suganya/.rvm/gems/ruby-2.1.1@rb/gems/activerecord-3.2.21/lib/active_record        /connection_adapters/abstract_mysql_adapter.rb:245:in `query'
  /home/suganya/.rvm/gems/ruby-2.1.1@rb/gems/activerecord-3.2.21/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:245:in `block in execute'
   /home/suganya/.rvm/gems/ruby-2.1.1@rb/gems/activerecord-3.2.21/lib/active_record/connection_adapters/abstract_adapter.rb:280:in `block in log'
  /home/suganya/.rvm/gems/ruby-2.1.1@rb/gems/activesupport-3.2.21/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
   /home/suganya/.rvm/gems/ruby-2.1.1@rb/gems/activerecord-3.2.21/lib/active_record/connection_adapters/abstract_adapter.rb:275:in `log'
  /home/suganya/.rvm/gems/ruby-2.1.1@rb/gems/activerecord-3.2.21/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:245:in `execute'
  /home/suganya/.rvm/gems/ruby-2.1.1@rb/gems/activerecord-3.2.21/lib/active_record/connection_adapters/mysql2_adapter.rb:213:in `execute'
  /home/suganya/.rvm/gems/ruby-2.1.1@rb/gems/activerecord-3.2.21/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:259:in `execute_and_free'
   /home/suganya/.rvm/gems/ruby-2.1.1@rb/gems/activerecord-3.2.21/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:426:in `columns'
   /home/suganya/.rvm/gems/ruby-2.1.1@rb/gems/activerecord-3.2.21/lib/active_record/connection_adapters/schema_cache.rb:12:in `block in initialize'
  </code></pre>
  
  <p>I don't know what am I doing wrong?</p>
  
  <pre><code> /home/suganya/academics/reportbee/app/models/constant_cache.rb:4:in `caches_constants'
    /home/suganya/academics/reportbee/app/models/role.rb:14:in `&lt;class:Role&gt;'
   /home/suganya/academics/reportbee/app/models/role.rb:1:in `&lt;top (required)&gt;'
  </code></pre>
  
  <p>In Role.rb</p>
  
  <pre><code> class Role &lt; ActiveRecord::Base
       has_many :allotments
       has_many :users, :through =&gt; :allotments
  
        serialize :possible_display_names, Array
  
       validates :name, presence: true, uniqueness: true
  
     scope :accessible, -&gt; { where( :accessible =&gt; true ) }
  
   CLASS_TEACHER_DISPLAY_NAME = 'Class Teacher'
  
     extend ConstantCache::ClassMethods
     caches_constants :name, :converter =&gt; :titleize 
  end
  </code></pre>