Un array - colocar un br cada 3 item

[gerry18_2]

Disculpen no puedo adaptarlo a este codigo con BASE DE DATOS . me podrian ayudar porfavor?
de antemano muchas gracias

Código PHP:

  <?
 
$sql="SELECT * FROM producto where estado=1";
$res=mysql_query($sql);
$numero = mysql_num_rows($res);    
$i = 0;
$row = 0;
 
 
while($registro=mysql_fetch_array($res))
    {
    
 
?>    
                                                            
                                            
 
                                                <div class="col-3">
 
                                                    <div class="indent1">
 
                                                        <h5><? echo $registro["producto"]; ?></h5><br>
 
                                                        <img alt="" src="<? echo $registro["imagen1"]; ?>" class="img-indent" width="135" height="125" /><br>
 
                                                        <strong><? echo $numero; ?></strong><br>
 
                                                        <b>Precio: <span><a href="#"><? echo $registro["precio"]?></a></span></b><br>
 
                                                        <? echo $registro["cantidad"]?> En Stock
 
                                                    </div>
 
                                                </div>    
 
 
                                                
                                            
                                                
                                                
                                    <?
                                
                                                        
                                                        }
                                                    ?>