title: Duplicate unicode entry error on the unique column - mysql
body: <p>I have a table <code>Labels</code> with 2 columns:</p>
  
  <pre><code>+-------------+--------------+-------------+
  | Column Name |     Type     |     Key     |
  +-------------+--------------+-------------+
  | id          | integer      | primary key |
  | label       | varchar(255) | unique      |
  +-------------+--------------+-------------+
  </code></pre>
  
  <p>In this table, I already have a record as the following:
  <code>id: 1, label: 'café'</code></p>
  
  <p>And now I want to add more record as the following:
  <code>id: auto, label: 'cafe'</code></p>
  
  <p>But when I try to insert, duplicate error appear</p>
  
  <pre><code>(1062, "Duplicate entry 'cafe' for key 'label_2'") [SQL: u'INSERT INTO vocabulary (label) VALUES (%s)'] [parameters: (u'cafe',)]
  </code></pre>
  
  <p>Could you guys help me in that case?
  Some more information about my database: character set: utf8, collate: utf8mb4_unicode_ci</p>
  
  <p>UPDATE: create table</p>
  
  <pre><code>CREATE TABLE `labels` (
    `id` int(11) NOT NULL AUTO_INCREMENT,
    `label` varchar(255) DEFAULT NULL,
    PRIMARY KEY (`id`),
    UNIQUE KEY `label_2` (`label`),
    KEY `label` (`label`)
  ) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;
  </code></pre>