first you have to translate date to mysql format (if using mysql)
function ToMysql($date)
{
return preg_replace("/(\d{1,2})\/(\d{1,2})\/(\d{2,4})/","\3-\2-\1",$date
}
and then build the sql query
$sql_query="select * from table where date>='".toMysql($to_date)."' and date<='".toMysql($from_date)."'";
and execute the query the way you like