CREATE TABLE `documents` (
  `document_id` int(11) NOT NULL,
  `merchant_id` int(11) NOT NULL,
  `document_type` smallint(6) default NULL,
  `id` int(11) NOT NULL auto_increment,
  `location` varchar(100) default NULL,
  `processing_state_id` int(11) default NULL,
  PRIMARY KEY  (`id`),
  KEY `i_processing_state_id` (`processing_state_id`),
  CONSTRAINT `FK_processing_state_id` FOREIGN KEY (`processing_state_id`) REFERENCES `processing_states` (`processing_state_id`)
)

CREATE TABLE `processing_states` (
  `id` int(11) NOT NULL auto_increment,
  `processing_state_id` int(11) NOT NULL,
  `description` varchar(50) default NULL,
  PRIMARY KEY  (`id`),
  UNIQUE KEY `i_processing_state_id` (`processing_state_id`)
)