title: Does MySQL overwrite a column of same value on update?
body: <p>When updating a table in MySQL, for example:</p>
  <blockquote>
  <p><strong>Table</strong> <code>user</code></p>
  </blockquote>
  <pre><code>user_id | user_name
  
  1         John
  2         Joseph
  3         Juan
  </code></pre>
  <p>If I run the query</p>
  <pre><code>UPDATE `user` SET user_name = 'John' WHERE user_id = 1
  </code></pre>
  <p>Will MySQL write the same value again or ignore it since it's the same content?</p>