mysqli prepared statements with between clause
<p>My question is similar to [this][1] but the solution provided there doesn't work for me.
I have a DB and I have one column called <code>birth</code> that contains a date in the format <code>year-day-month 00:00:00</code>. Now I want to extract from the DB all the records which birth is between two dates. 
The <code>birth</code> value has been inserted in the DB with this code</p>

<pre><code>$date =  $day . "-" . $month. "-" . $year;
$a = strptime($date, '%d-%m-%Y');
$DB_date = date('Y-m-d H:i:s',mktime(0, 0, 0, $a['tm_mon']+1, $a['tm_mday'], $a['tm_year']+1900));
</code></pre>

<p>To extract the dates I am using this code:</p>

<pre><code>$stmt = $conn-&gt;prepare('SELECT * FROM database WHERE `birth` BETWEEN ? AND ?');
$start_date = '1990-01-01';
$stop_date = '1995-01-01';
$stmt-&gt;bind_param('ss',$start_date,$stop_date);
$stmt-&gt;execute();
$result = $stmt-&gt;get_result();
</code></pre>

<p>but it doesn't find anything so <code>$result-&gt;num_rows</code> is equal to <code>0</code> and it doesn't give any errors so the problem must be in the comparison of the dates. </p>