What are the benefits of only_full_group_by mode? : <p>I updated mysql and I went from MySQL Version 5.6.17 to version 5.7.14</p>

<p>Since I have errors on my sql queries</p>

<p>Indeed, many of my queries look like this:</p>

<pre><code>SELECT count (id) as nbr, lic from prep WHERE key = '18'
</code></pre>

<p>And I have this error:</p>

<blockquote>
  <p>1140 - In aggregated query without GROUP BY, expression #2 of SELECT list contains nonaggregated column 'operator.preparation.orig_lic';
  this is incompatible with sql_mode=only_full_group_by</p>
</blockquote>

<p>After some research, I learn that Mysql 5.7.14 activates ONLY_FULL_GROUP_BY by default</p>

<p>Why is it enabled by default?</p>

<p>What is the best solution (for performance)? Disable ONLY_FULL_GROUP_BY or add a 'group by' on my query?</p>

<p>Thank you</p>
