title: Why navicat writes key instead of foreign key in CREATE TABLE?
body: <pre><code>CREATE TABLE IF NOT EXISTS `trl_bill` (
    `bill_id` int(11) NOT NULL AUTO_INCREMENT,
    `fee` double NOT NULL DEFAULT '0',
    `begin_date` date NOT NULL,
    `end_date` date NOT NULL,
    `is_paid` tinyint(4) NOT NULL DEFAULT '0',
    `request_id` int(11) NOT NULL,
    PRIMARY KEY (`bill_id`),
    KEY `request_id` (`request_id`) USING BTREE
  ) ENGINE=InnoDB DEFAULT CHARSET=utf8 ROW_FORMAT=FIXED AUTO_INCREMENT=1 ;
  </code></pre>
  
  <p>This is my table sql, i use navicat to design my database, why it writes <code>KEY</code> instead of <code>FOREIGN KEY</code>?</p>