Does MySQL overwrite a column of same value on update?
<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>