title: Why does MySQL return a message like 'returned an empty result set' or 'n row(s) affected'?
body: <p>Why does MySQL return <code># MySQL returned an empty result set (i.e. zero rows).</code> and <code>3 row(s) affected.</code>? Is there anything wrong in my SQL statements?</p>
  
  <pre><code>CREATE TABLE IF NOT EXISTS `test` (
    `id` mediumint(8) unsigned NOT NULL AUTO_INCREMENT,
    `order` mediumint(8) NOT NULL,
    `url` varchar(70) COLLATE utf8_unicode_ci NOT NULL,
    `title` varchar(70) COLLATE utf8_unicode_ci NOT NULL,
    `content` text COLLATE utf8_unicode_ci,
    PRIMARY KEY (`id`),
    UNIQUE KEY `url` (`url`)
  ) ENGINE=MyISAM  DEFAULT CHARSET=utf8 AUTO_INCREMENT=1;
  
  # MySQL returned an empty result set (i.e. zero rows).
  
  INSERT INTO `test` (`id`, `order`, `url`, `title`, `content`) VALUES
  (52338, 1, '', 'Home', 'content'),
  (70104, 2, 'about', 'About', 'content'),
  (27034, 3, 'portfolio', 'Portfolio', 'content');
  # 3 row(s) affected.
  </code></pre>