$query = "SELECT * FROM product_id_1";

$result = mysql_query($query);

while( $record = mysql_fetch_array($result) ){

$array[] = $record['username'];

$unique_array = array_unique($array);

}


foreach( $unique_array as $list ){
    echo $list.'<br/>';
}

$query = 'SELECT username, COUNT(*) AS username_count FROM product_id_1 GROUP BY username';

$result = mysql_query($query);

while ($record = mysql_fetch_object($result)) {

    echo $record->username;

    echo $record->username_count;
}

SELECT COUNT(1) AS username_count, username
FROM
    product_id_1
GROUP BY
    username