将varchar中的日期与mysql和php进行比较

I am trying to compare two dates in a column called " fecha_registro " , this column is varchar (100), I'm trying to compare him with this date code:

<?php

$host = "localhost";
$user = "root";
$pass = "";
$db   = "gimnasio";

mysql_connect($host, $user, $pass);
mysql_select_db($db);

$from = "2010-02-06";
$to = "2015-11-08";

$consulta = mysql_query("SELECT id_cliente FROM clientes WHERE fecha_registro BETWEEN '$from' AND '$to'");
$cantidad = mysql_num_rows($consulta);

echo $cantidad;

?>

the problem is that you never find any record when multiple records that meet that pattern

The structure of the "clients" table is this :

enter image description here

And the records like this:

enter image description here

please , as I fix this ?

try this

 SELECT id_cliente FROM clientes WHERE  
 DATE_FORMAT(STR_TO_DATE(fecha_registro, '%Y-%c-%e'), '%Y-%m-%d')
 BETWEEN '$from' AND '$to'

You can try by this way

SELECT id_cliente FROM clientes WHERE  
STR_TO_DATE(fecha_registro, '%Y-%m-%d')
BETWEEN '$from' AND '$to'